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June 22, 2021, 09:45:13 am

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Topics - Geoffw

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THE WOOD - STREAMING ONLINE
SHOWING FROM
TUE 22 JUN - SAT 03 JUL 2021
PRICE:
PAY WHAT YOU CAN
Torch Theatre Company presents: THE WOOD

WRITTEN BY OWEN THOMAS • DIRECTED BY PETER DORAN  BASED ON AN IDEA BY IFAN HUW DAFYDD

 "A tale of friendship, love and sacrifice set against the backdrop of a world in flames..."
From acclaimed Welsh playwright Owen Thomas, writer of the award-winning Grav, comes a digitally streamed version of the stage play originally written to commemorate the centenary of the end of World War I. Inspired by a true story.  Originally toured to packed out theatres across Wales in 2018, The Wood is a powerful, moving piece of theatre that lends itself beautifully to the screen. The streamed version reunites the original cast that toured in 2018; Ifan Huw Dafydd as Dan and Gwydion Rhys as Billy, alongside the original creative team; Director Peter Doran and Designer Sean Crowley.

The Wood was recorded on stage as live at the Torch Theatre, Milford Haven, under Covid-19 guidelines during lockdown 2021.

To book click here
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Treffgarne Rocks Pembrokeshire - a waxing crescent moon greets Venus as dusk falls!

FXT41489-Edit.jpg
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 543 2021 June 13

We're delighted that the Society for Popular Astronomy's free Electronic News Bulletins have gained many hundreds of subscribers since we first issued them more than 23 years ago!

They remain free, but if you are not already a member of the SPA, we hope you will consider joining, and supporting the UK's liveliest astronomical society, with members worldwide. You can easily sign up online. https://www.popastro.com/main_spa1/join-the-spa-now/

EUROPA'S INTERIOR HOT ENOUGH TO FUEL SEAFLOOR VOLCANOES
NASA

Jupiter's moon Europa has an icy crust covering a vast, global ocean. The rocky layer underneath may be hot enough to melt, leading to undersea volcanoes.  New research shows that volcanic activity may have occurred on the seafloor of Jupiter's moon Europa in the recent past - and may still be happening. The upcoming Europa Clipper mission, targeting a 2024 launch, will swoop close to the icy moon and take measurements that may shed light on the recent findings. Scientists have strong evidence that Europa harbours an enormous ocean between its icy crust and rocky interior. The new work shows how the moon may have enough internal heat to partially melt this rocky layer, a process that could feed volcanoes on the ocean floor. The recent 3D modelling of how this internal heat is produced and transferred is the most detailed and thorough examination yet of the effect this interior heating has on the moon. The key to Europa's rocky mantle being hot enough to melt lies with the
massive gravitational pull Jupiter has on its moons. As Europa revolves around the gas giant, the icy moon's interior flexes. The flexing forces energy into the moon's interior, which then seeps out as heat (think of how repeatedly bending a paperclip generates heat). The more the moon's interior flexes, the more heat is generated.

The research, published recently in Geophysical Research Letters, models in detail how Europa's rocky part may flex and heat under the pull of Jupiter's gravity. It shows where heat dissipates and how it melts that rocky mantle, increasing the likelihood of volcanoes on the seafloor.  Underwater volcanoes, if present, could power hydrothermal systems like those that fuel life at the bottom of Earth's oceans. On Earth, when seawater comes into contact with hot magma, the interaction results in chemical energy. And it is chemical energy from these hydrothermal systems, rather than from sunlight, that helps support life deep in our own oceans. Volcanic activity on Europa's seafloor would be one way to support a potential habitable environment in that moon's ocean.

PREVIOUSLY UNKNOWN ENERGY SOURCE AT CENTRE OF MILKY WAY
University of Massachusetts Amherst

New research reveals, with unprecedented clarity, details of violent phenomena in the centre of our galaxy. The images, published recently in Monthly Notices of the Royal Astronomical Society, which hints at a previously unknown interstellar mechanism that may govern the energy flow and potentially the evolution of the Milky Way. Astronomers know the centres of galaxies are where the action is and play an enormous role in their evolution. And yet, whatever has happened in the centre of our own galaxy is hard to study, despite its relative proximity to Earth, because it is obscured by a dense fog of gas and dust. Researchers simply can't see the centre, even with the Hubble Space Telescope. However, astronomers used the Chandra X-Ray Observatory, which "sees" X-rays, rather than the rays of visible light that we perceive with our own eyes. These X-rays are capable of penetrating the obscuring fog -- and the results are stunning. The findings give the clearest picture yet of a pair of X-ray-emitting plumes that are emerging from the region near the massive black hole lying at the centre of our galaxy. Even more intriguing is the discovery of an X-ray thread called G0.17-0.41, located near the southern plume. This thread reveals a new phenomenon - it is evidence of an ongoing magnetic field reconnection event. The thread probably represents "only the tip of the reconnection iceberg."

A magnetic field reconnection event is what happens when two opposing magnetic fields are forced together and combine with one another, releasing an enormous amount of energy. It's a violent process and is known to be responsible for such well-known phenomena as solar flares, which produce space weather powerful enough to disrupt power grids and communications systems here on Earth. They also produce the spectacular Northern Lights. Scientists now think that magnetic reconnection also occurs in interstellar space and tends to take place at the outer boundaries of the expanding plumes driven out of our galaxy's centre. What is the total amount of energy outflow at the centre of the galaxy? How is it produced and transported? And how does it regulate the galactic ecosystem? These are the fundamental questions whose answers will help to unlock the history of our galaxy. Though much work remains to be done, the new map points the way. For more information, including additional images and video, visit the Chandra X-Ray Observatory's Galactic Center website.

PROBING INTO ORIGINS OF COSMIC RAYS
American Institute of Physics

Cosmic rays are high-energy atomic particles continually bombarding Earth's surface at nearly the speed of light. Our planet's magnetic field shields the surface from most of the radiation generated by these particles. Still, cosmic rays can cause electronic malfunctions and are the leading concern in planning for space missions. Researchers know cosmic rays originate from the multitude of stars in the Milky Way, including our Sun, and other galaxies. The difficulty is tracing the particles to specific sources, because the turbulence of interstellar gas, plasma, and dust causes them to scatter and re-scatter in different directions. Researchers developed a simulation model to better understand these and other cosmic ray transport characteristics, with the goal of developing algorithms to enhance existing detection techniques. Brownian motion theory is generally employed to study cosmic ray trajectories. Much like the random motion of pollen particles in a pond, collisions between cosmic rays within fluctuating magnetic fields cause the particles to propel in different directions. But this classic diffusion approach does not adequately address the different propagation rates affected by diverse interstellar environments and long spells of cosmic voids. Particles can become trapped for a time in magnetic fields, which slow them down, while others are thrust into higher speeds through star explosions.

To address the complex nature of cosmic ray travel, the researchers use a stochastic scattering model, a collection of random variables that evolve over time. The model is based on geometric Brownian motion, a classic diffusion theory combined with a slight trajectory drift in one direction. In their first experiment, they simulated cosmic rays moving through interstellar space and interacting with localized magnetized clouds, represented as tubes. The rays travel undisturbed over a long period of time. They are interrupted by chaotic interaction with the magnetized clouds, resulting in some rays reemitting in random directions and others remaining trapped. Monte Carlo numerical analysis, based on repeated random sampling, revealed ranges of density and reemission strengths of the interstellar magnetic clouds, leading to skewed, or heavy-tailed, distributions of the propagating cosmic rays. The analysis denotes marked superdiffusive behaviour. The model's predictions agree well with known transport properties in complex interstellar media.

DARK MATTER REVEALS BRIDGES BETWEEN GALAXIES
Penn State

A new map of dark matter in the local Universe reveals several previously undiscovered filamentary structures connecting galaxies. The map, developed using machine learning by researchers, could enable studies about the nature of dark matter as well as about the history and future of our local Universe. Dark matter is an elusive substance that makes up 80% of the Universe. It also provides the skeleton for what cosmologists call the cosmic web, the large-scale structure of the universe that, due to its gravitational influence, dictates the motion of galaxies and other cosmic material. However, the distribution of local dark matter is currently unknown because it cannot be measured directly. Researchers must instead infer its distribution based on its gravitational influence on other objects in the universe, like galaxies. Ironically, it's easier to study the distribution of dark matter much further away because it reflects the very distant past, which is much less complex. Over time, as the large-scale structure of the Universe has grown, the complexity of the Universe has increased, so it is inherently harder to make measurements about dark matter locally. Previous attempts to map the cosmic web started with a model of the early Universe and then simulated the evolution of the model over billions of years. However, this method is computationally intensive and so far has not been able to produce results detailed enough to see the local Universe. In the new study, the researchers took a completely different approach, using machine learning to build a model that uses information about the distribution and motion of galaxies to predict the distribution of dark matter.

The researchers built and trained their model using a large set of galaxy simulations, called Illustris-TNG, which includes galaxies, gasses, other visible matter, as well as dark matter. The team specifically selected simulated galaxies comparable to those in the Milky Way and ultimately identified which properties of galaxies are needed to predict the dark matter distribution. When given certain information, the model can essentially fill in the gaps based on what it has looked at before. The map from the models doesn't perfectly fit the simulation data, but researchers can still reconstruct very detailed structures. They found that including the motion of galaxies -- their radial peculiar velocities -- in addition to their distribution drastically enhanced the quality of the map and allowed them to see these details. The research team then applied their model to real data from the local Universe from the Cosmicflow-3 galaxy catalogue. The catalogue contains comprehensive data about the distribution and movement of more than 17 thousand galaxies in the vicinity of the Milky Way -- within 200 megaparsecs. The map successively reproduced known prominent structures in the local Universe, including the "local sheet" -- a region of space containing the Milky Way, nearby galaxies in the "local group," and galaxies in the Virgo cluster -- and the "local void" -- a relatively empty region of space next to the local group. Additionally, it identified several new structures that require further investigation, including smaller filamentary structures that connect galaxies. Having a local map of the cosmic web opens up a new chapter of cosmological study such as how the distribution of dark matter relates to other emission data, which will help us understand the nature of dark matter. And we can study these filamentary structures directly, these hidden bridges between galaxies. For example, it has been suggested that the Milky Way and Andromeda galaxies may be slowly moving toward each other, but whether they may collide in many billions of years remains unclear. Studying the dark matter filaments connecting the two galaxies could provide important insights into their future.

HUNT FOR HUM OF GRAVITATIONAL WAVES
Australian National University

The hunt for the never before heard "hum" of gravitational waves caused by neutron stars has just got a lot easier, thanks to an international team of researchers. Gravitational waves have only been detected from black holes and neutron stars colliding, major cosmic events that cause huge bursts that ripple through space and time. The research team are now turning their eagle eye to spinning neutron stars to detect the waves. Unlike the massive bursts caused by black holes or neutron stars colliding, the researchers say single spinning neutron stars have a bulge or "mountain" only a few millimetres high, which may produce a steady constant stream or "hum" of gravitational waves. The researchers are using their methods that detected gravitational waves for the first time in 2015 to capture this steady soundtrack of the stars over the thunderous noise of massive black holes and dense neutron stars colliding. They say it's like trying to capture the squeak of a mouse in the middle of a stampeding herd of elephants. If successful, it would be the first detection of a gravitational wave event that didn't involve the collision of massive objects like black holes or neutron stars. The collision of dense neutron stars sends a "burst" of gravitational waves rippling through the Universe. Neutron stars are mystery objects and astronomers don't really understand what they are made up of, or how many types of them exist. But what is known is that when they collide, they send incredible bursts of gravitational waves across the Universe. In contrast, the gentle hum of a spinning neutron star is very faint and almost impossible to detect. If astronomers can manage to detect this hum, they will be able to look deep into the heart of a neutron star and unlock its secrets. Neutron stars represent the densest form of matter in the Universe before a black hole will form. Searching for their gravitational waves allows us to probe nuclear matter states that simply can't be produced in laboratories on Earth.

TWO NEW MISSIONS TO VENUS
NASA

Part of NASA's Discovery Program, the missions aim to understand how Venus became an inferno-like world when it has so many other characteristics similar to ours - and may have been the first habitable world in the solar system, complete with an ocean and Earth-like climate. These investigations are the final selections from four mission concepts NASA picked in February 2020 as part of the agency's Discovery 2019 competition. Following a competitive, peer-review process, the two missions were chosen based on their potential scientific value and the feasibility of development plans. The project teams will now work to finalize their requirements, designs, and development plans. NASA is awarding approximately $500 million per mission for development. Each is expected to launch in the 2028-2030 timeframe. The selected missions are: DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging). DAVINCI+ will measure the composition of Venus' atmosphere to understand how it formed and evolved, as well as determine whether the planet ever had an ocean. The mission consists of a descent sphere that will plunge through the planet's thick atmosphere, making precise measurements of noble gases and other elements to understand why Venus' atmosphere is a runaway hothouse compared the Earth's. In addition, DAVINCI+ will return the first high resolution pictures of the unique geological features on Venus known as "tesserae," which may be comparable to Earth's continents, suggesting that Venus has plate tectonics. This would be the first U.S.-led mission to Venus' atmosphere since 1978, and the results from DAVINCI+ could reshape our understanding of terrestrial planet formation in our solar system and beyond.

VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) VERITAS will map Venus' surface to determine the planet's geologic history and understand why it developed so differently than Earth. Orbiting Venus with a synthetic aperture radar, VERITAS will chart surface elevations over nearly the entire planet to create 3D reconstructions of topography and confirm whether processes such as plate tectonics and volcanism are still active on Venus. VERITAS also will map infrared emissions from Venus' surface to map its rock type, which is largely unknown,and determine whether active volcanoes are releasing water vapour into the atmosphere.

FURTHER DELAY FOR JAMES WEBB TELESCOPE
ARS Technica

The James Webb Space Telescope won't launch as scheduled on Halloween this year--however, the delay may only be a few weeks. Last summer, NASA and the European Space Agency (ESA) set an October 31, 2021, launch date for the $10 billion telescope. The instrument, which is the largest science observatory ever placed into space, will launch on a European Ariane 5 rocket from a spaceport in French Guiana. Now, however, three considerations have pushed the launch into November or possibly early December. The telescope's director for launch services said that there are a "combination of different factors" to consider when setting a new launch date. These factors include shipment of the telescope, the readiness of the Ariane 5 rocket, and the readiness of the spaceport in South America as well. A new launch date will not be announced until later this summer or early autumn. NASA plans to ship the telescope to the launch site by boat late this summer. (NASA is keeping precise plans vague due to concerns about piracy at sea.) The launch campaign, which begins when the telescope arrives in French Guiana, requires 55 days. The rocket is also not ready. The Ariane 5 booster, a venerable rocket in service for more than 25 years, has been grounded since August 2020 due to a payload fairing issue. However, officials with Arianespace, which manages launch for the Ariane 5, said the fairing issue's cause has been diagnosed and addressed with a redesign. Two Ariane 5 launches are scheduled before Webb's launch to ensure that the fairing issue has been fixed. (Those launches are scheduled for July and August, but delays are possible.) Finally, there are concerns about the spaceport itself, where operations have been limited by COVID-19. Vaccines are not yet widely available in French Guiana, and officials have said that if virus activity worsens, it could further slow operations.

Bulletin compiled by Clive Down
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Family History / LostCousins Newsletter
June 07, 2021, 10:52:01 am
Banging your head against a 'brick wall'?  Perhaps this newsletter will inspire you to change your tactics....

What makes a 'brick wall' crack?
Oldest 'brick wall' comes crashing down
Save 25% on Ancestry DNA in the UK ENDS 20TH JUNE
Don't just read the Masterclass.....
Exporting servants to Western Australia in the 1850s and 1890sScottish Roman Catholic registers online
Marriage registers: follow up
An amazing sequence of marriages and other chance discoveries
Adoption stories: forced to give up their child
The last veteran of Dunkirk and D-Day?
Get better results from your newspaper searches
What's available from your local library?
Royal Succession
Realising the potential of DNA: gene therapy
Probability and family history (part 2)
Peter's Tips

To proceed to the newsletter click the link below (or else, highlight it, copy it, then paste it into your browser).

https://lostcousins.com/newsletters2/jun21news.htm
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Pembrokeshire County Council is proposing to amend its Off Street parking order (car parks).

It follows a full review of the service, which was considered by Cabinet in March 2020 who agreed to proceed to consultation. This has been delayed until now because of Covid-19.

The review proposes that the parking service reaches a full cost recovery position (it currently runs at a loss) and also provides income for the following:
·                     protecting the future of public toilets situated in car parks
·                     providing additional street lighting in car parks
·                     increasing the budget for minor improvement works and general maintenance
·                     rolling out cashless parking payment machines

Some key proposed changes include:
·                     amending seasonal charges to all year charges
·                     increasing the cost of a coastal permit
·                     introducing a new maximum stay on Goodwick Bridge car park (the flags car park)

The consultation on the proposal (called a variation order) can be viewed here:
https://haveyoursay.pembrokeshire.gov.uk/proposed-variation-to-off-street-parking-places-order . The link also gives you access to a number of documents to assist in explaining the reasoning, as well as maps.

The deadline for comments is 16 June.

Feedback from the consultation will be incorporated into a report to Cabinet for their final decision.
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Hywel Dda University Health Board (UHB) is asking the people of Carmarthenshire, Ceredigion and Pembrokeshire to help it further shape and deliver future services by taking part in a six-week engagement exercise.
The public is also being asked to nominate sites for a new hospital based four criteria:

The nominated site must be within the zone between and including St Clears in Carmarthenshire and Narberth in Pembrokeshire. This location is the most central to most of the population in the south of the Hywel Dda area.
The nominated site should be a minimum of 35 acres of reasonably developable land.
The nominated site should have realistic prospects of obtaining planning permission for a new hospital.
There should be appropriate transport infrastructure for a major hospital site.


FOR FULL DETAILS CLICK HERE
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Astronomy Group / Night Sky in June 2021
June 02, 2021, 03:42:32 pm
Night Sky in June

A change of seasons arrives as stargazers in the southern hemisphere enjoy long nights to make up for cooling
temperatures, while northerners enjoy summer at the expense of much shorter nights! But there's plenty to see this month as Jupiter and Saturn grow in brightness and size, rising in the southeast after midnight. Mars slowly eases itself westwards towards the sun after more than a year in the night sky, but it goes out in style as it passes through the Beehive star cluster late in the month. Mercury is lost in the sun's glare for most of June. But Venus sits low and bright in the evening sky over the northwestern horizon after sunset at its most northerly declination of the year.

Here's what to see in the night (and day) sky this month..................SEE ATTACHMENT BELOW

The Night Sky in June 2021.pdf
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 542 2021 May 30

We're delighted that the Society for Popular Astronomy's free Electronic News Bulletins have gained many hundreds of subscribers since we first issued them more than 23 years ago!

They remain free, but if you are not already a member of the SPA, we hope you will consider joining, and supporting the UK's liveliest astronomical society, with members worldwide. You can easily sign up online. https://www.popastro.com/main_...

And now, here is our latest round-up of news.

ALIEN RADIOACTIVE ELEMENT PROMPTS RETHINK
Australian National University

The first-ever discovery of an extraterrestrial radioactive isotope on Earth has scientists rethinking the origins of the elements on our planet. The tiny traces of plutonium-244 were found in ocean crust alongside radioactive iron-60. The two isotopes are evidence of violent cosmic events in the vicinity of Earth millions of years ago. Star explosions, or supernovae create many of the heavy elements in the periodic table, including those vital for human life, such as iron, potassium and iodine. To form even heavier elements, such as gold, uranium and plutonium it was thought that a more violent event may be needed, such as two neutron stars merging. However, a new study suggests a more complex picture. Any plutonium-244 and iron-60 that existed when the Earth formed from interstellar gas and dust over four billion years ago has long since decayed, so current traces of them must have originated from recent cosmic events in space. The dating of the sample confirms two or more supernova explosions occurred near Earth. The data could be the first evidence that supernovae do indeed produce plutonium-244. Or perhaps it was already in the interstellar medium before the supernova went off, and it was pushed across the solar system together with the supernova ejecta. The VEGA accelerator at Australian Nuclear Science and Technology Organisation, (ANSTO) in Sydney was used to identify the tiny traces of the plutonium-244.

HEAVY METAL VAPOURS FOUND IN COMETS
ESO

A new study using data from the European Southern Observatory's Very Large Telescope (ESO's VLT) has shown that iron and nickel exist in the atmospheres of comets throughout our Solar System, even those far from the Sun. A separate study who also used ESO data, reported that nickel vapour is also present in the icy interstellar comet 2I/Borisov. This is the first time heavy metals, usually associated with hot environments, have been found in the cold atmospheres of distant comets. Astronomers know that heavy metals exist in comets' dusty and rocky interiors. But, because solid metals don't usually "sublimate" (become gaseous) at low temperatures, they did not expect to find them in the atmospheres of cold comets that travel far from the Sun. Nickel and iron vapours have now even been detected in comets observed at more than 480 million kilometres from the Sun, more than three times the Earth-Sun distance. One team found iron and nickel in comets' atmospheres in approximately equal amounts. Material in our Solar System, for example that found in the Sun and in meteorites, usually contains about ten times more iron than nickel. This new result therefore has implications for astronomers' understanding of the early Solar System, though the team is still decoding what these are. While the Belgian team has been studying these "fossil" objects with ESO's VLT for nearly 20 years, they had not spotted the presence of nickel and iron in their atmospheres until now. The team used data from the Ultraviolet and Visual Echelle Spectrograph (UVES) instrument on ESO's VLT, which uses spectroscopy, to analyse the atmospheres of comets at different distances from the Sun. This technique allows astronomers to reveal the chemical makeup of cosmic objects: each chemical element leaves a unique signature -- a set of lines -- in the spectrum of the light from the objects. The team had spotted weak, unidentified spectral lines in their UVES data and on closer inspection noticed that they were signalling the presence of neutral atoms of iron and nickel. A reason why the heavy elements were difficult to identify is that they exist in very small amounts: the team estimates that for each 100 kg of water in the comets' atmospheres there is only 1 g of iron, and about the same amount of nickel.

Another remarkable study shows that heavy metals are also present in the atmosphere of the interstellar comet 2I/Borisov. A team in Poland observed this object, the first alien comet to visit our Solar System, using the X-shooter spectrograph on ESO's VLT when the comet flew by about a year and a half ago. They found that 2I/Borisov's cold atmosphere contains gaseous nickel. The finding is surprising because, before the two studies, gases with heavy metal atoms had only been observed in hot environments, such as in the atmospheres of ultra-hot exoplanets or evaporating comets that passed too close to the Sun. 2I/Borisov was observed when it was some 300 million kilometres away from the Sun, or about twice the Earth-Sun distance. Studying interstellar bodies in detail is fundamental to science because they carry invaluable information about the alien planetary systems they originate from. The two studies show that 2I/Borisov and Solar System comets have even more in common than previously thought.

STAR WILL COME WITHIN 24 LIGHT DAYS OF SUN
Universe Today

Within the Milky Way, there are an estimated 200 to 400 billion stars, all of which orbit around the centre of our galaxy in a coordinated cosmic dance. As they orbit, stars in the galactic disk (where our Sun is located) periodically shuffle about and get closer to one another. At times, this can have a drastic effect on the star that experience a close encounter, disrupting their systems and causing planets to be ejected. Knowing when stars will make a close encounter with our Solar System, and how it might shake-up objects within it, is therefore a concern to astronomers. Using data collected by the Gaia Observatory, two researchers with the Russian Academy of Sciences (RAS) determined that a handful of stars will be making close passes by our Solar System in the future, one of which will stray pretty close! The study relied on astrometric data from the Gaia mission's Early Data Release 3 (EDR3), which revealed kinematic characteristics of stars that are expected to pass within 3.26 light-years (1 Parsec) with the Solar System in the future. To start things off simple: our Solar System is composed of eight designated planets and several minor (aka. dwarf) planets orbiting our main sequence G-type yellow dwarf Sun, which is surrounded by outer ring of icy objects known as the Kuiper Belt. Beyond this, at a distance of roughly light-years from the Sun (0.5 parsecs), is a massive cloud of icy debris known as the Oort Cloud, which is where long-period comets originate.

These comets are generally the result of objects making close flybys with the Solar System and knocking objects loose, to the point that they periodically fly through Solar System and around the Sun before heading back out. The outer edge of the Oort Cloud is estimated to be 0.5 parsecs (1.6 light-years) from our Sun, which makes them particularly responsive to perturbations from a number of sources. For astronomers, the process of searching for stars that may have flown by our Solar System in the past (and which may pass us by in the future) began in the 1960s. The research has improved as more sophisticated instruments have become available, leading to more detailed catalogues on nearby celestial objects. In order to know which stars will make a close encounter, you need to know their distance and their three velocities. These consist the two properties of proper motion - right ascension, declination - and radial velocity. Once you have all that, you can conduct astrometry, which is the precise measurement of the positions and movements of stars and other celestial bodies. It was for this very purpose that the ESA's Hipparcos satellite (1989-1993) and Gaia Observatory (2013-present) were created. Thanks to the precise data they have provided, and the updated catalogues on millions of stars and other celestial objects, astronomers are able to determine which of them are likely to make a close encounter in the future.

In the end, one star, designated 4270814637616488064 in the Gaia EDR3 database, will be making a particularly close encounter a little over a million years from now. Better-known as Gliese 710 (HIP 89825), this variable K-type orange dwarf star is about 60% as massive as our Sun and located some 62 light years from Earth in the Serpens constellation. The showed that Gliese 710 would be making its close flyby 1.32 million years from now and would pass within 0.20 parsecs (0.65 light-years) of our Sun. So, assuming human beings (or their genetic progeny) are still living in the Solar System 2.32 million years from now, they will be treated to some added comet activity. This could pose some hazards, depending on the trajectories of these comets and the extent of human infrastructure in space. Or it could just mean more opportunities for backyard astronomy, or whatever the futuristic equivalent is.

NOVA BECOMES MUCH BRIGHTER
National Astronomical Observatory of Japan

A new star named V1405 Cas Nova which was discovered by an amateur astronomer in Japan has kept growing brighter over two months and it can be spotted with the naked eye now. Nakamura Yuji of the city of Kameyama in Mie Prefecture in central Japan found the star on March18. It is in the direction of Cassiopeia. It had increased its brightness 50-fold to a star magnitude level of five by May 9. Less than 20 new stars are found every year but most of them grow darker after growing brighter for several days. Experts say that it is rare that a new star grows brighter for a few months and becomes bright enough to be seen without a telescope. Astronomers believe that a major explosive phenomenon occurred on the surface of the star. It's a very rare and interesting phenomenon and researchers hope that many people will be encouraged to look up to the night sky and stars.

HOW AND WHEN MILKY WAY CAME TOGETHER
Ohio State University

New research provides the best evidence to date into the timing of how our early Milky Way came together, including the merger with a key satellite galaxy. Using relatively new methods in astronomy, the researchers were able to identify the most precise ages currently possible for a sample of about a hundred red giant stars in the galaxy. With this and other data, the researchers were able to show what was happening when the Milky Way merged with an orbiting satellite galaxy, known as Gaia-Enceladus, about 10 billion years ago. Evidence suggests that when the merger occurred, the Milky Way had already formed a large population of its own stars, Many of those "homemade" stars ended up in the thick disc in the middle of the galaxy, while most that were captured from Gaia-Enceladus are in the outer halo of the galaxy. The merging event with Gaia-Enceladus is thought to be one of the most important in the Milky Way's history, shaping how we observe it today. By calculating the age of the stars, the researchers were able to determine, for the first time, that the stars captured from Gaia-Enceladus have similar or slightly younger ages compared to the majority of stars that were born inside the Milky Way. A violent merger between two galaxies can't help but shake things up. Results showed that the merger changed the orbits of the stars already in the galaxy, making them more eccentric.

Astronomers compared the stars' movements to a dance, where the stars from the former Gaia-Enceladus move differently than those born within the Milky Way. The stars even "dress" differently, with stars from outside showing different chemical compositions from those born inside the Milky Way. The researchers used several different approaches and data sources to conduct their study. One way the researchers were able to get such precise ages of the stars was through the use of asteroseismology, a relatively new field that probes the internal structure of stars. Asteroseismologists study oscillations in stars, which are sound waves that ripple through their interiors. That allows us to get very precise ages for the stars, which are important in determining the chronology of when events happened in the early Milky Way. The study also used a spectroscopic survey, called APOGEE, which provides the chemical composition of stars -- another aid in determining their ages. Astronomers now intend to apply this approach to larger samples of stars, and to include even more subtle features of the frequency spectra. This will eventually lead to a much sharper view of the Milky Way's assembly history and evolution, creating a timeline of how our galaxy developed.

DOES THE MILKY WAY MOVE LIKE A SPINNING TOP? B:
Instituto de Astrofísica de Canarias (IAC)

An investigation questions one of the most interesting findings about the dynamics of the Milky Way in recent years: that the precession, or the wobble in the axis of rotation of the disc warp is incorrect. The Milky Way is a spiral galaxy, which means that it is composed, among other components, of a disc of stars, gas and dust, in which the spiral arms are contained. At first, it was thought that the disc was completely flat, but for some decades now it is known that the outermost part of the disc is distorted into what is called a "warp": in one direction it is twisted upwards, and in the opposite direction downwards. The stars, the gas, and the dust are all warped, and so are not in the same plane as the extended inner part of the disc, and an axis perpendicular to the planes of the warp defines their rotation. In 2020, an investigation announced the detection of the precession of the warp of the Milky Way disc, which means that the deformation in this outer region is not static, but that just like a spinning top the orientation of its axis is itself rotating with time. Furthermore, these researchers found that it was quicker than the theories predicted, a cycle every 600-700 million years, some three times the time it takes the Sun to travel once round the centre of the Galaxy. Precession is not a phenomenon which occurs only in galaxies, it also happens to our planet. As well as its annual revolution around the Sun, and its rotation period of 24 hours, the axis of the Earth precesses, which implies that the celestial pole is not always close to the present pole star, but that (as an example) 14,000 years ago it was close to the star Vega.

Now, a new study has taken into account the variation of the amplitude of the warp with the ages of the stars. The study concludes that, using the warp of the old stars whose velocities have been measured, it is possible that the precession can disappear, or at least become slower than what is presently believed. To arrive at this result the researchers have used data from the Gaia Mission of the European Space Agency (ESA), analysing the positions and velocities of hundreds of millions of stars in the outer disc. In previous studies it had not been noticed that the stars which are a few tens of millions of years old, such as the Cepheids, have a much larger warp than that of the stars visible with the Gaia mission, which are thousands of millions of years old. "This does not necessarily mean that the warp does not precess at all, it could do so, but much more slowly, and we are probably unable to measure this motion until we obtain better data.

36 DWARF GALAXIES HAD SIMULTANEOUS 'BABY BOOM'
Rutgers University

Three dozen dwarf galaxies far from each other had a simultaneous "baby boom" of new stars, an unexpected discovery that challenges current theories on how galaxies grow and may enhance our understanding of the Universe. Galaxies more than 1 million light-years apart should have completely independent lives in terms of when they give birth to new stars. But galaxies separated by up to 13 million light-years slowed down and then simultaneously accelerated their birth rate of stars. It appears that these galaxies are responding to a large-scale change in their environment in the same way a good economy can spur a baby boom. Regardless of whether these galaxies were next-door neighbours or not, they stopped and then started forming new stars at the same time, as if they'd all influenced each other through some extra-galactic social network. The simultaneous decrease in the stellar birth rate in the 36 dwarf galaxies began 6 billion years ago, and the increase began 3 billion years ago. Understanding how galaxies evolve requires untangling the many processes that affect them over their lifetimes (billions of years). Star formation is one of the most fundamental processes. The stellar birth rate can increase when galaxies collide or interact, and galaxies can stop making new stars if the gas (mostly hydrogen) that makes stars is lost.

Star formation histories can paint a rich record of environmental conditions as a galaxy "grew up." Dwarf galaxies are the most common but least massive type of galaxies in the Universe, and they are especially sensitive to the effects of their surrounding environment. The 36 dwarf galaxies included a diverse array of environments at distances as far as 13 million light-years from the Milky Way. The environmental change the galaxies apparently responded to must be something that distributes fuel for galaxies very far apart. That could mean encountering a huge cloud of gas, for example, or a phenomenon in the Universe we don't yet know about. The scientists used two methods to compare star formation histories. One uses light from individual stars within galaxies; the other uses the light of a whole galaxy, including a broad range of colours. The full impact of the discovery is not yet known as it remains to be seen how much our current models of galaxy growth need to be modified to understand this surprise. If the result cannot be explained within our current understanding of cosmology, that would be a huge implication

HUBBLE TRACKS DOWN FAST RADIO BURSTS
NASA/Goddard Space Flight Center

Astronomers using the Hubble Space Telescope have traced the locations of five brief, powerful radio blasts to the spiral arms of five distant galaxies. Called fast radio bursts (FRBs), these extraordinary events generate as much energy in a thousandth of a second as the Sun does in a year. Because these transient radio pulses disappear in much less than the blink of an eye, researchers have had a hard time tracking down where they come from, much less determining what kind of object or objects is causing them. Therefore, most of the time, astronomers don't know exactly where to look. Locating where these blasts are coming from, and in particular, what galaxies they originate from, is important in determining what kinds of astronomical events trigger such intense flashes of energy. The new Hubble survey of eight FRBs helps researchers narrow the list of possible FRB sources. The first FRB was discovered in archived data recorded by the Parkes radio observatory on July 24, 2001. Since then astronomers have uncovered up to 1,000 FRBs, but they have only been able to associate roughly 15 of them to particular galaxies. In the Hubble study, astronomers not only pinned all of them to host galaxies, but they also identified the kinds of locations they originated from. Hubble observed one of the FRB locations in 2017 and the other seven in 2019 and 2020. The galaxies in the Hubble study existed billions of years ago. Astronomers, therefore, are seeing the galaxies as they appeared when the universe was about half its current age. Many of them are as massive as our Milky Way. The observations were made in ultraviolet and near-infrared light with Hubble's Wide Field Camera 3. Ultraviolet light traces the glow of young stars strung along a spiral galaxy's winding arms. The researchers used the near-infrared images to calculate the galaxies' mass and find where older populations of stars reside. The images display a diversity of spiral-arm structure, from tightly wound to more diffuse, revealing how the stars are distributed along these prominent features. A galaxy's spiral arms trace the distribution of young, massive stars. However, the Hubble images reveal that the FRBs found near the spiral arms do not come from the very brightest regions, which blaze with the light from hefty stars. The images help support a picture that the FRBs likely do not originate from the youngest, most massive stars.

These clues helped the researchers rule out some of the possible triggers of types of these brilliant flares, including the explosive deaths of the youngest, most massive stars, which generate gamma-ray bursts and some types of supernovae. Another unlikely source is the merger of neutron stars, the crushed cores of stars that end their lives in supernova explosions. These mergers take billions of years to occur and are usually found far from the spiral arms of older galaxies that are no longer forming stars. The team's Hubble results, however, are consistent with the leading model that FRBs originate from young magnetar outbursts. Magnetars are a type of neutron star with powerful magnetic fields. They're called the strongest magnets in the Universe, possessing a magnetic field that is 10 trillion times more powerful than a refrigerator door magnet. Astronomers last year linked observations of an FRB spotted in our Milky Way galaxy with a region where a known magnetar resides. Owing to their strong magnetic fields, magnetars are quite unpredictable. In this case, the FRBs are thought to come from flares from a young magnetar. Massive stars go through stellar evolution and becomes neutron stars, some of which can be strongly magnetized, leading to flares and magnetic processes on their surfaces, which can emit radio light. Our study fits in with that picture and rules out either very young or very old progenitors for FRBs. The observations also helped the researchers strengthen the association of FRBs with massive, star-forming galaxies. Previous ground-based observations of some possible FRB host galaxies did not as clearly detect underlying structure, such as spiral arms, in many of them. Astronomers, therefore, could not rule out the possibility that FRBs originate from a dwarf galaxy hiding underneath a massive one. In the new Hubble study, careful image processing and analysis of the images allowed researchers to rule out underlying dwarf galaxies. Although the Hubble results are exciting, the researchers say they need more observations to develop a more definitive picture of these enigmatic flashes and better pinpoint their source.

CHARTING EXPANSION OF UNIVERSE WITH SUPERNOVAE
National Institutes of Natural Sciences

An international research team analyzed a database of more than 1000 supernova explosions and found that models for the expansion of the Universe best match the data when a new time dependent variation is introduced. If proven correct with future, higher-quality data from the Subaru Telescope and other observatories, these results could indicate still unknown physics working on the cosmic scale. Edwin Hubble's observations over 90 years ago showing the expansion of the Universe remain a cornerstone of modern astrophysics. But when you get into the details of calculating how fast the Universe was expanding at different times in its history, scientists have difficulty getting theoretical models to match observations. To solve this problem, a team of researchers analysed a catalogue of 1048 supernovae which exploded at different times in the history of the Universe. The team found that the theoretical models can be made to match the observations if one of the constants used in the equations, appropriately called the Hubble constant, is allowed to vary with time. There are several possible explanations for this apparent change in the Hubble constant. A likely but boring possibility is that observational biases exist in the data sample. To help correct for potential biases, astronomers are using Hyper Suprime-Cam on the Subaru Telescope to observe fainter supernovae over a wide area. Data from this instrument will increase the sample of observed supernovae in the early Universe and reduce the uncertainty in the data. But if the current results hold-up under further investigation, if the Hubble constant is in fact changing, that opens the question of what is driving the change. Answering that question could require a new, or at least modified, version of astrophysics.

MOST ANCIENT SPIRAL GALAXY WITH DISCOVERED
National Institutes of Natural Sciences

Analyzing data obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), researchers found a galaxy with a spiral morphology by only 1.4 billion years after the Big Bang. This is the most ancient galaxy of its kind ever observed. The discovery of a galaxy with a spiral structure at such an early stage is an important clue to solving the classic questions of astronomy: "How and when did spiral galaxies form?" The Milky Way Galaxy, where we live, is a spiral galaxy. Spiral galaxies are fundamental objects in the Universe, accounting for as much as 70% of the total number of galaxies. However, other studies have shown that the proportion of spiral galaxies declines rapidly as we look back through the history of the Universe. So, when were the spiral galaxies formed? Researchers noticed a galaxy called BRI 1335-0417 in the ALMA Science Archive. The galaxy existed 12.4 billion years ago and contained a large amount of dust, which obscures the starlight. This makes it difficult to study this galaxy in detail with visible light. On the other hand, ALMA can detect radio emissions from carbon ions in the galaxy, which enables us to investigate what is going on in the galaxy. The researchers found a spiral structure extending 15,000 light-years from the centre of the galaxy. This is one third of the size of the Milky Way Galaxy. The estimated total mass of the stars and interstellar matter in BRI 1335-0417 is roughly equal to that of the Milky Way. Then the question becomes, how was this distinct spiral structure formed in only 1.4 billion years after the Big Bang?

The researchers considered multiple possible causes and suggested that it could be due to an interaction with a small galaxy. BRI 1335-0417 is actively forming stars and the researchers found that the gas in the outer part of the galaxy is gravitationally unstable, which is conducive to star formation. This situation is likely to occur when a large amount of gas is supplied from outside, possibly due to collisions with smaller galaxies. The fate of BRI 1335-0417 is also shrouded in mystery. Galaxies that contain large amounts of dust and actively produce stars in the ancient Universe are thought to be the ancestors of the giant elliptical galaxies in the present Universe. In that case, BRI 1335-0417 changes its shape from a disk galaxy to an elliptical one in the future. Or, contrary to the conventional view, the galaxy may remain a spiral galaxy for a long time. BRI 1335-0417 will play an important role in the study of galaxy shape evolution over the long history of the Universe.

METHOD TO REDUCE STRAY LIGHT ON SPACE TELESCOPES
University of Liege

A team of researchers has developed a method to identify the contributors and origins of stray light on space telescopes. This is a major advance in the field of space engineering that will help in the acquisition of even finer space images and the development of increasingly efficient space instruments. Space telescopes are becoming more and more powerful. Technological developments in recent years have made it possible, for example, to observe objects further and further into the Universe or to measure the composition of the Earth's atmosphere with ever greater precision. However, there is still one factor limiting the performance of these telescopes: stray light. A phenomenon that has been known fora long time, stray light results in light reflections (ghost reflections between lenses, scattering, etc.) that damage the quality of images and often lead to blurred images. Until now, the methods for checking and characterizing this stray light during the development phase of the telescopes have been very limited, making it possible to "just" know whether or not the instrument was sensitive to the phenomenon, forcing engineers to revise all their calculations in positive cases, leading to considerable delays in the commissioning of these advanced tools. Researchers have developed a revolutionary method for solving this problem by using a femto-second pulsed laser to send light beams to illuminate the telescope. Thanks to this, and using an ultra-fast detector (of the order of 10-9 seconds of resolution, i.e. a thousandth of a millionth of a second), the image is measured and the different stray light effects at different times. In addition to this decomposition, each of the contributors can be measured using their arrival times, which are directly related to the optical path, and thus know the origin of the problem. This method could lead to a small revolution in the field of high-performance space instruments and responds to an urgent problem that has been unresolved until now. In the near future, researchers intend to continue the development of this method, to increase its TRL (Technology Readiness Level) and bring it to an industrial level. An industrial application is already planned for the FLEX (Fluorescence Explorer) project, an Earth observation telescope that is part of ESA's Living Planet Program. The researchers hope to be able to apply it to scientific instruments as well.

Bulletin compiled by Clive Down
(c) 2021 The Society for Popular Astronomy
The Society for Popular Astronomy has been helping beginners in amateur astronomy -- and more experienced observers -- for over 60 years. If you are not a member, you may be missing something. Membership rates are extremely reasonable, starting at just £23 a year in the UK. You will receive our bright bi-monthly magazine Popular Astronomy, help and advice in pursuing your hobby, the chance to hear top astronomers at our regular meetings, and other benefits. The best news is that you can join online right now with a credit or debit card at our lively website: www.popastro.com
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U3A Walkers / Monday Walkers Back in Action!
May 10, 2021, 08:08:03 pm
Nearly thirty Pembrokeshire U3A members met at Bosherston National Trust Car Park today to for their first walk for many, many months.

We follow the path alongside the beautiful lily ponds to Broad Haven beach, walk along the beach and up to the car park at Broad Haven before a short walk along the road to Woodlands. This took us back to the lily ponds where we follow the path on the other side via 2 bridges back to the car park.

A walk of about 3.5 miles with the weather being kind as the rain showers passed us by. An ideal first walk of the season.  Such a pity we couldn't round it off with a nice lunch.

Our thank to Richard and Irene for leading the walk and to Carol Matthew for organising it.

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Astronomy Group / Eclipses visble from St David's
May 02, 2021, 04:54:58 pm
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Astronomy Group / The Night Sky in May 2021
May 02, 2021, 01:30:34 pm
The Night Sky in May 2021


Moon Photo: Geoff Winterman

It's another busy month in the night sky as the Eta Aquarid meteor shower peaks in the first week of May, Venus and Mercury adorn the western sky after sunset, and Saturn and Jupiter get closer and bigger in the pre-dawn sky. And for much of the world, a total lunar eclipse occurs during the last week of May.

Here's what to see in the night sky this month....... See attachment for details
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 540 2021 May 2

Here is the latest round-up of news from the Society for Popular Astronomy.  The SPA is arguably Britain's liveliest astronomical society, with members all over the world. We accept subscription payments online at our secure site and can take credit and debit cards. You can join or renew via a secure server or just see how much we have to offer by visiting http://www.popastro.com/

MARS COULD SUPPORT PRESENT DAY MICROBIAL LIFE
Brown University

As NASA's Perseverance rover begins its search for ancient life on the surface of Mars, a new study suggests that the Martian subsurface might be a good place to look for possible present-day life on the Red Planet. The study looked at the chemical composition of Martian meteorites -- rocks blasted off of the surface of Mars that eventually landed on Earth. The analysis determined that those rocks, if in consistent contact with water, would produce the chemical energy needed to support microbial communities similar to those that survive in the unlit depths of the Earth. Because these meteorites may be representative of vast swaths of the Martian crust, the findings suggest that much of the Mars subsurface could be habitable. In recent decades, scientists have discovered that Earth's depths are home to a vast biome that exists largely separated from the world above. Lacking sunlight, these creatures survive using the by-products of chemical reactions produced when rocks come into contact with water. One of those reactions is radiolysis, which occurs when radioactive elements within rocks react with water trapped in pore and fracture space. The reaction breaks water molecules into their constituent elements, hydrogen and oxygen. The liberated hydrogen is dissolved in the remaining groundwater, while minerals like pyrite soak up free oxygen to form sulphate minerals. Microbes can ingest the dissolved hydrogen as fuel and use the oxygen preserved in the sulphates to "burn" that fuel. In places like Canada's Kidd Creek Mine, these "sulphate-reducing" microbes have been found living more than a mile underground, in water that hasn't seen the light of day in more than a billion years.

For this new study, the researchers wanted to see if the ingredients for radiolysis-driven habitats could exist on Mars. They drew on data from NASA's Curiosity rover and other orbiting spacecraft, as well as compositional data from a suite of Martian meteorites, which are representative of different parts of the planet's crust. The researchers were looking for the ingredients for radiolysis: radioactive elements like thorium, uranium and potassium; sulphide minerals that could be converted to sulphate; and rock units with adequate pore space to trap water. The study found that in several different types of Martian meteorites, all the ingredients are present in adequate abundances to support Earth-like habitats. This was particularly true for regolith breccias -- meteorites sourced from crustal rocks more than 3.6 billion years old -- which were found to have the highest potential for life support. Unlike Earth, Mars lacks a plate tectonics system that constantly recycle crustal rocks. So these ancient terrains remain largely undisturbed. The researchers say the findings help make the case for an exploration program that looks for signs of present-day life in the Martian subsurface. Prior research has found evidence of an active groundwater system on Mars in the past, the researchers say, and there's reason to believe that groundwater exists today. One recent study, for example, raised the possibility of an underground lake lurking under the planet's southern ice cap. This new research suggests that wherever there's groundwater, there's energy for life. While there are certainly technical challenges involved in subsurface exploration, they aren't as insurmountable as people may think. A drilling operation wouldn't require "a Texas-sized oil rig," and recent advances in small drill probes could soon put the Martian depths within reach.

NEW SUPER-EARTH FOUND ORBITING RED DWARF STAR
Instituto de Astrofísica de Canarias (IAC)

In recent years there has been an exhaustive study of red dwarf stars to find exoplanets in orbit around them. These stars have effective surface temperatures between 2400 and 3700 K (over 2000 degrees cooler than the Sun), and masses between 0.08 and 0.45 solar masses. In this context, a team of researchers specializing in the search for planets around this type of stars, has discovered a super-Earth orbiting the star GJ 740, a red dwarf star situated some 36 light years from Earth. The planet orbits its star with a period of 2.4 days and its mass is around 3 times the mass of Earth. Because the star is so close to the Sun, and the planet so close to the star, this new super-Earth could be the object of future researches with very large diameter telescopes towards the end of this decade. The data also indicate the presence of a second planet with an orbital period of 9 years, and a mass comparable to that of Saturn (close to 100 Earth masses), although its radial velocity signal could be due to the magnetic cycle of the star (similar to that of the Sun), so that more data are needed to confirm that the signal is really due to a planet. The Kepler mission, recognised at one of the most successful in detecting exoplanets using the transit method (which is the search for small variations in the brightness of a star caused by the transit between it and ourselves of planets orbiting around it), has discovered a total of 156 new planets around cool stars. From its data it has been estimated that this type of stars harbours an average of 2.5 planets with orbital periods of less than 200 days. Cool stars are also an ideal target for the search for planets via the radial velocity method. This method is based on the detection of small variations in the velocity of a star due to the gravitational attraction of a planet in orbit around it, using spectroscopic observations. Since the discovery in 1998 of the first radial velocity signal of an exoplanet around a cool star, until now, a total of 116 exoplanets has been discovered around this class of stars using the radial velocity method. This detection was possible due to a six year observing campaign with HARPS-N, complemented with measurements with the CARMENES spectrograph on the 3.5m telescope at the Calar Alto Observatory (Almería) and HARPS, on the 3.6m telescope at the La Silla Observatory (Chile), as well as photometric support from the ASAP and EXORAP surveys.

HYDROXYL MOLECULE DETECTED IN EXOPLANET
Trinity College Dublin

Astronomers have detected a new chemical signature in the atmosphere of an extrasolar planet . The hydroxyl radical (OH) was found on the dayside of the exoplanet WASP-33b. This planet is a so-called 'ultra-hot Jupiter', a gas-giant planet orbiting its host star much closer than Mercury orbits the Sun and therefore reaching atmospheric temperatures of more than 2,500° C (hot enough to melt most metals). This is the first direct evidence of OH in the atmosphere of a planet beyond the Solar System. It shows not only that astronomers can detect this molecule in exoplanet atmospheres, but also that they can begin to understand the detailed chemistry of this planetary population. In the Earth's atmosphere, OH is mainly produced by the reaction of water vapour with atomic oxygen. It is a so-called 'atmospheric detergent' and plays a crucial role in the Earth's atmosphere to purge pollutant gasses that can be dangerous to life (e.g., methane, carbon monoxide). In a much hotter and bigger planet like WASP-33b, where astronomers have previously detected signs of iron and titanium oxide gas) OH plays a key role in determining the chemistry of the atmosphere through interactions with water vapour and carbon monoxide. Most of the OH in the atmosphere of WASP-33b is thought to have been produced by the destruction of water vapour due to the extremely high temperature.

To make this discovery, the team used the InfraRed Doppler (IRD) instrument at the 8.2-meter diameter Subaru Telescope located in the summit area of Maunakea in Hawai`i (about 4,200 m above sea level). This new instrument can detect atoms and molecules through their 'spectral fingerprints", unique sets of dark absorption features superimposed on the rainbow of colours (or spectrum) that are emitted by stars and planets. As the planet orbits its host star, its velocity relative to the Earth changes with time. Just like the siren of an ambulance or the roar of a racing car's engine changes pitch while speeding past us, the frequencies of light (e.g., colour) of these spectral fingerprints change with the velocity of the planet. This allows astronomers to separate the planet's signal from its bright host star, which normally overwhelms such observations, despite modern telescopes being nowhere near powerful enough to take direct images of such 'hot Jupiter' exoplanets. By taking advantage of the unique capabilities of IRD, the astronomers were able to detect the tiny signal from hydroxyl in the planet's atmosphere. While WASP-33b may be a giant planet, these observations are the testbed for the next-generation facilities like the Thirty Meter Telescope and the European Extremely Large Telescope in searching for biosignatures on smaller and potentially rocky worlds, which might provide hints to one of the oldest questions of humankind: 'Are we alone?'

RCW 120 NEBULA IS YOUNGER THAN BELIEVED
West Virginia University

In the southern sky, situated about 4,300 light years from Earth, lies RCW 120, an enormous glowing cloud of gas and dust. This cloud, known as an emission nebula, is formed of ionized gases and emits light at various wavelengths. An international team of researchers studied RCW 120 to analyze the effects of stellar feedback, the process by which stars inject energy back into their environment. Their observations showed that stellar winds cause the region to expand rapidly, which enabled them to constrain the age of the region. These findings indicate that RCW 120 must be less than 150,000 years old, which is very young for such a nebula. About seven light years from the centre of RCW 120 lies the boundary of the cloud, where a plethora of stars are forming. How are all of these stars being formed? To answer that question, we need to dig deep into the origin of the nebula. RCW 120 has one young, massive star in its centre, which generates powerful stellar winds. The stellar winds from this star are much like those from our own Sun, in that they throw material out from their surface into space. This stellar wind shocks and compresses the surrounding gas clouds. The energy that is being input into the nebula triggers the formation of new stars in the clouds, a process known as "positive feedback" because the presence of the massive central star has a positive effect on future star formation. The team used SOFIA (the Stratospheric Observatory for Infrared Astronomy) to study the interactions of massive stars with their environment.

SOFIA is an airborne observatory consisting of a 2.7-metre telescope carried by a modified Boeing 747SP aircraft. SOFIA observes in the infrared regime of the electromagnetic spectrum, which is just beyond what humans can see. For observers on the ground, water vapour in the atmosphere blocks much of the light from space that infrared astronomers are interested in measuring. However, its cruising altitude of 13 km puts SOFIA above most of the water vapour, allowing researchers to study star-forming regions in a way that would not be possible from the ground. Overnight, the in-flight observatory observes celestial magnetic fields, star-forming regions (like RCW 120), comets and nebulae. Thanks to the new upGREAT receiver that was installed in 2015, the airborne telescope can make more precise maps of large areas of the sky than ever before. The research team opted to observe the spectroscopic [CII] line with SOFIA, which is emitted from diffuse ionized carbon in the star-forming region. Using their [CII] observations from SOFIA, the research team found that RCW 120 is expanding at 15 km/s, which is incredibly fast for a nebula. From this expansion speed, the team was able to put an age limit on the cloud and found that RCW 120 is much younger than previously believed. With the age estimate, they were able to infer the time it took for the star formation at the boundary of the nebula to kick in after the central star had been formed. These findings suggest that positive feedback processes occur on very short timescales and point to the idea that these mechanisms could be responsible for the high star formation rates that occurred during the early stages of the Universe.

NEW ALL-SKY MAP OF MILKY WAY'S OUTER REACHES
NASA/Jet Propulsion Laboratory

Astronomers using data from NASA and ESA (European Space Agency) telescopes have released a new all-sky map of the outermost region of our galaxy. Known as the galactic halo, this area lies outside the swirling spiral arms that form the Milky Way's recognizable central disk and is sparsely populated with stars. Though the halo may appear mostly empty, it is also predicted to contain a massive reservoir of dark matter, a mysterious and invisible substance thought to make up the bulk of all the mass in the Universe. The data for the new map comes from ESA's Gaia mission and NASA's Near Earth Object Wide Field Infrared Survey Explorer, or NEOWISE, which operated from 2009 to 2013 under the moniker WISE. The study makes use of data collected by the spacecraft between 2009 and 2018. The new map reveals how a small galaxy called the Large Magellanic Cloud (LMC) -- so named because it is the larger of two dwarf galaxies orbiting the Milky Way -- has sailed through the Milky Way's galactic halo like a ship through water, its gravity creating a wake in the stars behind it. The LMC is located about 160,000 light-years from Earth and is less than one-quarter the mass of the Milky Way. Though the inner portions of the halo have been mapped with a high level of accuracy, this is the first map to provide a similar picture of the halo's outer regions, where the wake is found -- about 200,000 light-years to 325,000 light-years from the galactic centre. Previous studies have hinted at the wake's existence, but the all-sky map confirms its presence and offers a detailed view of its shape, size, and location. This disturbance in the halo also provides astronomers with an opportunity to study something they can't observe directly: dark matter. While it doesn't emit, reflect, or absorb light, the gravitational influence of dark matter has been observed across the Universe. It is thought to create the scaffolding on which galaxies are built, such that without it, galaxies would fly apart as they spin. Dark matter is estimated to be five times more common in the Universe than all the matter that emits and/or interacts with light, from stars to planets to gas clouds.

Although there are multiple theories about the nature of dark matter, all of them indicate that it should be present in the Milky Way's halo. If that's the case, then as the LMC sails through this region, it should leave a wake in the dark matter as well. The wake observed in the new star map is thought to be the outline of this dark matter wake; the stars are like leaves on the surface of this invisible ocean, their position shifting with the dark matter. The interaction between the dark matter and the Large Magellanic Cloud has big implications for our galaxy. As the LMC orbits the Milky Way, the dark matter's gravity drags on the LMC and slows it down. This will cause the dwarf galaxy's orbit to get smaller and smaller, until the galaxy finally collides with the Milky Way in about 2 billion years. These types of mergers might be a key driver in the growth of massive galaxies across the Universe. In fact, astronomers think the Milky Way merged with another small galaxy about 10 billion years ago. The authors of the paper also think the new map -- along with additional data and theoretical analyses -- may provide a test for different theories about the nature of dark matter, such as whether it consists of particles, like regular matter, and what the properties of those particles are. The team mapped the positions of over 1,300 stars in the halo. The challenge arose in trying to measure the exact distance from Earth to a large portion of those stars: It's often impossible to figure out whether a star is faint and close by or bright and far away. After identifying stars most likely located in the halo (because they were not obviously inside our galaxy or the LMC), the team looked for stars belonging to a class of giant stars with a specific light "signature" detectable by NEOWISE. Knowing the basic properties of the selected stars enabled the team to figure out their distance from Earth and create the new map. It charts a region starting about 200,000 light-years from the Milky Way's centre, or about where the LMC's wake was predicted to begin, and extends about 125,000 light-years beyond that. One model by the Arizona team, included in the new study, predicted the general structure and specific location of the star wake revealed in the new map. Once the data had confirmed that the model was correct, the team could confirm what other investigations have also hinted at: that the LMC is likely on its first orbit around the Milky Way. If the smaller galaxy had already made multiple orbits, the shape and location of the wake would be significantly different from what has been observed. Astronomers think the LMC formed in the same environment as the Milky Way and another nearby galaxy, M31, and that it is close to completing a long first orbit around our galaxy (about 13 billion years). Its next orbit will be much shorter due to its interaction with the Milky Way.

FAST-SPINNING BLACK HOLES NARROW DARK MATTER SEARCH
Massachusetts Institute of Technology

Ultralight bosons are hypothetical particles whose mass is predicted to be less than a billionth the mass of an electron. They interact relatively little with their surroundings and have thus far eluded searches to confirm their existence. If they exist, ultralight bosons such as axions would likely be a form of dark matter, the mysterious, invisible stuff that makes up 85 percent of the matter in the Universe. Now, physicists at MIT's LIGO Laboratory have searched for ultralight bosons using black holes -- objects that are mind-bending orders of magnitude more massive than the particles themselves. According to the predictions of quantum theory, a black hole of a certain mass should pull in clouds of ultralight bosons, which in turn should collectively slow down a black hole's spin. If the particles exist, then all black holes of a particular mass should have relatively low spins. But the physicists have found that two previously detected black holes are spinning too fast to have been affected by any ultralight bosons. Because of their large spins, the black holes' existence rules out the existence of ultralight bosons with masses between 1.3x10-13 electronvolts and 2.7x10-13 electronvolts -- around a quintillionth the mass of an electron. The study is also the first to use the spins of black holes detected by LIGO and Virgo, and gravitational-wave data, to look for dark matter. Ultralight bosons are being searched for across a huge range of super-light masses, from 1x10-33 electronvolts to 1x10-6 electronvolts. Scientists have so far used tabletop experiments and astrophysical observations to rule out slivers of this wide space of possible masses. Since the early 2000s, physicists proposed that black holes could be another means of detecting ultralight bosons, due to an effect known as superradiance.

If ultralight bosons exist, they could interact with a black hole under the right circumstances. Quantum theory posits that at a very small scale, particles cannot be described by classical physics, or even as individual objects. This scale, known as the Compton wavelength, is inversely proportional to the particle mass. As ultralight bosons are exceptionally light, their wavelength is predicted to be exceptionally large. For a certain mass range of bosons, their wavelength can be comparable to the size of a black hole. When this happens, superradiance is expected to quickly develop. Ultralight bosons are then created from the vacuum around a black hole, in quantities large enough that the tiny particles collectively drag on the black hole and slow down its spin. In their study, the team looked through all 45 black hole binaries reported by LIGO and Virgo to date. The masses of these black holes -- between 10 and 70 times the mass of the Sun -- indicate that if they had interacted with ultralight bosons, the particles would have been between 1x10-13 electronvolts and 2x10-11 electronvolts in mass. For every black hole, the team calculated the spin that it should have if the black hole was spun down by ultralight bosons within the corresponding mass range. From their analysis, two black holes stood out: GW190412 and GW190517. Just as there is a maximum velocity for physical objects -- the speed of light -- there is a top spin at which black holes can rotate. GW190517 is spinning at close to that maximum. The researchers calculated that if ultralight bosons existed, they would have dragged its spin down by a factor of two. The researchers also accounted for other possible scenarios for generating the black holes' large spins, while still allowing for the existence of ultralight bosons. For instance, a black hole could have been spun down by bosons but then subsequently sped up again through interactions with the surrounding accretion disk -- a disk of matter from which the black hole could suck up energy and momentum. In other words, it's unlikely that the black holes' high spins are due to an alternate scenario in which ultralight bosons also exist. Given the masses and high spins of both black holes, the researchers were able to rule out the existence of ultralight bosons with masses between 1.3x10-13 electronvolts and 2.7x10-13 electronvolts.

ROTATING INFANT GALAXY DISCOVERED WITH NATURAL COSMIC TELESCOPE
National Institutes of Natural Sciences

Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers found a rotating baby galaxy 1/100th the size of the Milky Way at a time when the Universe was only seven percent of its present age. Thanks to assistance by the gravitational lens effect, the team was able to explore for the first time the nature of small and dark "normal galaxies" in the early Universe, representative of the main population of the first galaxies, which greatly advances our understanding of the initial phase of galaxy evolution. Many of the galaxies that existed in the early Universe were so small that their brightness is well below the limit of the current largest telescopes on Earth and in Space, making difficult to study their properties and internal structure. However, the light coming from the galaxy named RXCJ0600-z6, was highly magnified by gravitational lensing, making it an ideal target for studying the properties and structure of a typical baby galaxies. Gravitational lensing is a natural phenomenon in which light emitted from a distant object is bent by the gravity of a massive body such as a galaxy or a galaxy cluster located in the foreground. The name "gravitational lensing" is derived from the fact that the gravity of the massive object acts like a lens. When we look through a gravitational lens, the light of distant objects is intensified and their shapes are stretched. In other words, it is a "natural telescope" floating in space. The ALMA Lensing Cluster Survey (ALCS) team used ALMA to search for a large number of galaxies in the early Universe that are enlarged by gravitational lensing. Combining the power of ALMA, with the help of the natural telescopes, the researchers are able to uncover and study fainter galaxies.

Why is it crucial to explore the faintest galaxies in the early Universe? Theory and simulations predict that the majority of galaxies formed few hundred millions years after the Big-Bang are small, and thus faint. Although several galaxies in the early Universe have been previously observed, those studied were limited to the most massive objects, and therefore the less representative galaxies, in the early Universe, because of telescopes capabilities. The only way to understand the standard formation of the first galaxies, and obtain a complete picture of galaxy formation, is to focus on the fainter and more numerous galaxies. The ALCS team performed a large-scale observation program that took 95 hours, which is a long time for ALMA observations, to observe the central regions of 33 galaxy clusters that could cause gravitational lensing. One of these clusters, called RXCJ0600-2007, is located in the direction of the constellation of Lepus, and has a mass 1000 trillion times that of the Sun. The team discovered a single distant galaxy that is being affected by the gravitational lens created by this natural telescope. ALMA detected the light from carbon ions and stardust in the galaxy and, together with data taken with the Gemini telescope, determined that the galaxy is seen as it was about 900 million years after the Big Bang (12.9 billion years ago). Further analysis of these data suggested that a part of this source is seen 160 times brighter than it is intrinsically. By precisely measuring the mass distribution of the cluster of galaxies, it is possible to "undo" the gravitational lensing effect and restore the original appearance of the magnified object. By combining data from Hubble Space Telescope and the European Southern Observatory's Very Large Telescope with a theoretical model, the team succeeded in reconstructing the actual shape of the distant galaxy RXCJ0600-z6. The total mass of this galaxy is about 2 to 3 billion times that of the Sun, which is about 1/100th of the size of our own Milky Way Galaxy. What astonished the team is that RXCJ0600-z6 is rotating. Traditionally, gas in the young galaxies was thought to have random, chaotic motion. Only recently has ALMA discovered several rotating young galaxies that have challenged the traditional theoretical framework, but these were several orders of magnitude brighter (larger) than RXCJ0600-z6. When the Thirty Meter Telescope and the Extremely Large Telescope are completed, they may be able to detect clusters of stars in the galaxy, and possibly even resolve individual stars. There is an example of gravitational lensing that has been used to observe a single star 9.5 billion light-years away, and this research has the potential to extend this to less than a billion years after the birth of the Universe.



Bulletin compiled by Clive Down

(c) 2021 The Society for Popular Astronomy

The Society for Popular Astronomy has been helping beginners in amateur astronomy -- and more experienced observers -- for over 60 years. If you are not a member, you may be missing something. Membership rates are extremely reasonable, starting at just £23 a year in the UK. You will receive our bright bi-monthly magazine Popular Astronomy, help and advice in pursuing your hobby, the chance to hear top astronomers at our regular meetings, and other benefits. The best news is that you can join online right now with a credit or debit card at our lively website: www.popastro.com
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22 April. The Lyrid meteor shower peaks in the early-morning hours. This is the first significant meteor shower since the Quadrantids in early January. The Lyrids display some 15-20 meteors per hour in good conditions. The moon, just two days past first quarter, may get in the way of the faintest meteors this year.  The Lyrids trace their apparent paths back to a point between the constellations Hercules and Lyra, both of which rise in the east around midnight. They're visible all night, but you may have more luck after midnight as the Earth turns into the meteor stream. The Lyrids have made a regular appearance for at least 2,500 years, longer than any other meteor shower. They happen as Earth passes through a stream of debris left by Comet C/1861 G1 (Thatcher).
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 539 2021 April 18

Here is the latest round-up of news from the Society for Popular Astronomy.  The SPA is arguably Britain's liveliest astronomical society, with members all over the world. We accept subscription payments online at our secure site and can take credit and debit cards. You can join or renew via a secure server or just see how much we have to offer by visiting http://www.popastro.com/

SOLAR VARIABILITY LINKED TO LA NINA EVENTS
National Center for Atmospheric Research/University Corporation for Atmospheric Research

A new study shows a correlation between the end of solar cycles and a switch from El Nino to La Nina conditions in the Pacific Ocean, suggesting that solar variability can drive seasonal weather variability on Earth. If the connection holds up, it could significantly improve the predictability of the largest El Nino and La Nina events, which have a number of seasonal climate effects over land. For example, the southern United States tends to be warmer and drier during a La Nina, while the northern U.S. tends to be colder and wetter. The appearance (and disappearance) of spots on the Sun -- the outwardly visible signs of solar variability -- have been observed by humans for hundreds of years. The waxing and waning of the number of sunspots takes place over approximately 11-year cycles, but these cycles do not have distinct beginnings and endings. This fuzziness in the length of any particular cycle has made it challenging for scientists to match up the 11-year cycle with changes happening on Earth. In the new study, the researchers rely on a more precise 22-year "clock" for solar activity derived from the Sun's magnetic polarity cycle, which they outlined as a more regular alternative to the 11-year solar cycle in several companion studies published recently in peer-reviewed journals. The 22-year cycle begins when oppositely charged magnetic bands that wrap the Sun appear near the star's polar latitudes, according to their recent studies. Over the cycle, these bands migrate toward the equator -- causing sunspots to appear as they travel across the mid-latitudes. The cycle ends when the bands meet in the middle, mutually annihilating one another in what the research team calls a terminator event.
hese terminators provide precise guideposts for the end of one cycle and the beginning of the next.

The researchers imposed these terminator events over sea surface temperatures in the tropical Pacific stretching back to 1960. They found that the five terminator events that occurred between that time and November 2010 all coincided with a flip from an El Nino (when sea surface temperatures are warmer than average) to a La Nina (when the sea surface temperatures are cooler than average). The end of the most recent solar cycle -- which is unfolding now -- is also coinciding with the beginning of a La Nina event. In fact, the researchers did a number of statistical analyses to determine the likelihood that the correlation was just a fluke. They found there was only a 1 in 5,000 chance or less (depending on the statistical test) that all five terminator events included in the study would randomly coincide with the flip in ocean temperatures. Now that a sixth terminator event -- and the corresponding start of a new solar cycle in 2020 -- has also coincided with an La Nina event, the chance of a random occurrence is even more remote, the authors said. The paper does not delve into what physical connection between the Sun and Earth could be responsible for the correlation, but the authors note that there are several possibilities that warrant further study, including the influence of the Sun's magnetic field on the amount of cosmic rays that escape into the solar system and ultimately bombard Earth. However, a robust physical link between cosmic rays variations and climate has yet to be determined. If further research can establish that there is a physical connection and that changes on the Sun are truly causing variability in the oceans, then we may be able to improve our ability to predict El Nino and La Nina events.

5,000 TONS OF EXTRATERRESTRIAL DUST FALL TO EARTH ANNUALLY
CNRS

Every year, our planet encounters dust from comets and asteroids. These interplanetary dust particles pass through our atmosphere and give rise to shooting stars. Some of them reach the ground in the form of micrometeorites. An international program conducted for nearly 20 years has determined that 5,200 tons per year of these micrometeorites reach the ground. Micrometeorites have always fallen on our planet. These interplanetary dust particles from comets or asteroids are particles of a few tenths to hundredths of a millimetre that have passed through the atmosphere and reached the Earth's surface. To collect and analyse these micrometeorites, six expeditions have taken place over the last two decades in the heart of Antarctica. It is an ideal collection spot due to the low accumulation rate of snow and the near absence of terrestrial dust. These expeditions have collected enough extraterrestrial particles (ranging from 30 to 200 micrometres in size), to measure their annual flux, which corresponds to the mass accreted on Earth per square metre per year. If these results are applied to the whole planet, the total annual flux of micrometeorites represents 5,200 tons per year. This is the main source of extraterrestrial matter on our planet, far ahead of larger objects such as meteorites, for which the flux is less than ten tons per year. A comparison of the flux of micrometeorites with theoretical predictions confirms that most micrometeorites probably come from comets (80%) and the rest from asteroids. This is valuable information to better understand the role played by these interplanetary dust particles in supplying water and carbonaceous molecules on the young Earth.

ODYSSEY ORBITER MAPS MARS FOR 20 YEARS
NASA

For two decades, the longest-lived spacecraft at the Red Planet has helped locate water ice, assess landing sites, and study the planet's mysterious moons. NASA's 2001 Mars Odyssey spacecraft launched 20 years ago on April 7, making it the oldest spacecraft still working at the Red Planet. The orbiter, which takes its name from Arthur C. Clarke's classic sci-fi novel "2001: A Space Odyssey" (Clarke blessed its use before launch), was sent to map the composition of the Martian surface, providing a window to the past so scientists could piece together how the planet evolved. But it's done far more than that, uncovering troves of water ice, serving as a crucial communications link for other spacecraft, and helping to pave the way not just for safer landings but also future astronauts. Look at almost any mapping study of the Martian surface, and it probably includes Odyssey data. For many years, the most complete global maps of Mars were made using Odyssey's infrared camera, called the Thermal Emission Imaging System, or THEMIS. The camera measures the surface temperature day and night, allowing scientists to determine what physical materials, such as rock, sand, or dust, exist. Its data reveals the presence of these materials based on how they heat up or cool down over the course of a Martian day. The net effect of two decades' worth of all that mapping? Scientists haven't just used the data to map valley networks and craters, they've also been able to spot sandstone, iron-rich rocks, salts, and more - findings that help lend deeper insight to Mars' story. THEMIS has sent back more than 1 million images since it began circling Mars. The images and maps it's produced highlight the presence of hazards, such as topographic features and boulders, but they also help ensure the safety of future astronauts by showing the location of resources such as water ice. This aids the Mars science community and NASA in deciding where to send landers and rovers - including the Perseverance rover, which touched down on Feb. 18, 2021.

From early on, Odyssey has served as a long-distance call centre for NASA's rovers and landers, sending their data back to Earth as part of the Mars Relay Network. The idea of Mars relay goes back to the 1970's, when the two Viking landers sent science data and images through an orbiter back to Earth. An orbiter can carry radios or antennas capable of sending back more data than a surface spacecraft. But Odyssey made the process routine when it began conveying data to and from NASA's Spirit and Opportunity rovers. Each day, the rovers could go somewhere new and send fresh images back to Earth. Through a relay like Odyssey, scientists got more data sooner, while the public got more Mars images to be excited over. Odyssey has supported over 18,000 relay sessions. These days, it shares the communications task with NASA's Mars Reconnaissance Orbiter and MAVEN, along with the ESA (European Space Agency) Trace Gas Orbiter. Odyssey has done such a thorough job of studying the Martian surface that scientists have started turning its THEMIS camera to capture unique views of Mars' moons Phobos and Deimos. As with the Martian surface, studying each moon's thermophysics helps scientists determine the properties of materials on their surfaces. Such information can offer glimmers into their past: It's unclear whether the moons are captured asteroids or chunks of Mars, blasted off the surface by an ancient impact. Future missions, like the Japanese Space Agency's Martian Moons eXploration (MMX) spacecraft, will seek to land on these moons. In the distant future, missions might even create bases on them for astronauts. And if they do, they'll rely on data from an orbiter that began its odyssey at the start of the millennium.

X-RAYS DETECTED FROM URANUS
Harvard-Smithsonian Center for Astrophysics

Astronomers have detected X-rays from Uranus for the first time, using NASA's Chandra X-ray Observatory. This result may help scientists learn more about this enigmatic ice giant planet in our solar system. Uranus is the seventh planet from the Sun and has two sets of rings around its equator. The planet, which has four times the diameter of Earth, rotates on its side, making it different from all other planets in the solar system. Since Voyager 2 was the only spacecraft to ever fly by Uranus, astronomers currently rely on telescopes much closer to Earth, like Chandra and the Hubble Space Telescope, to learn about this distant and cold planet that is made up almost entirely of hydrogen and helium. In the new study, researchers used Chandra observations taken in Uranus in 2002 and then again in 2017. They saw a clear detection of X-rays from the first observation, just analyzed recently, and a possible flare of X-rays in those obtained fifteen years later. What could cause Uranus to emit X-rays? The answer: mainly the Sun. Astronomers have observed that both Jupiter and Saturn scatter X-ray light given off by the Sun, similar to how Earth's atmosphere scatters the Sun's light. While the authors of the new Uranus study initially expected that most of the X-rays detected would also be from scattering, there are tantalizing hints that at least one other source of X-rays is present. If further observations confirm this, it could have intriguing implications for understanding Uranus. One possibility is that the rings of Uranus are producing X-rays themselves, which is the case for Saturn's rings. Uranus is surrounded by charged particles such as electrons and protons in its nearby space environment. If these energetic particles collide with the rings, they could cause the rings to glow in X-rays. Another possibility is that at least some of the X-rays come from auroras on Uranus, a phenomenon that has previously been observed on this planet at other wavelengths.

On Earth, we can see colourful light shows in the sky called auroras, which happen when high-energy particles interact with the atmosphere. X-rays are emitted in Earth's auroras, produced by energetic electrons after they travel down the planet's magnetic field lines to its poles and are slowed down by the atmosphere. Jupiter has auroras, too. The X-rays from auroras on Jupiter come from two sources: electrons traveling down magnetic field lines, as on Earth, and positively charged atoms and molecules raining down at Jupiter's polar regions. However, scientists are less certain about what causes auroras on Uranus. Chandra's observations may help figure out this mystery. Uranus is an especially interesting target for X-ray observations because of the unusual orientations of its spin axis and its magnetic field. While the rotation and magnetic field axes of the other planets of the solar system are almost perpendicular to the plane of their orbit, the rotation axis of Uranus is nearly parallel to its path around the Sun. Furthermore, while Uranus is tilted on its side, its magnetic field is tilted by a different amount, and offset from the planet's centre. This may cause its auroras to be unusually complex and variable. Determining the sources of the X-rays from Uranus could help astronomers better understand how more exotic objects in space, such as growing black holes and neutron stars, emit X-rays.

TRIO OF FAST-SPINNING BROWN DWARFS MAY REVEAL ROTATIONAL SPEED LIMIT
ESO

Brown dwarfs, sometimes known as "failed stars," can spin at upwards of 200,000 mph, but there may be a limit to how fast they can go. Using data from NASA's Spitzer Space Telescope, scientists have identified the three fastest-spinning brown dwarfs ever found. More massive than most planets but not quite heavy enough to ignite like stars, brown dwarfs are cosmic in-betweeners. And though they aren't as well-known as stars and planets to most people, they are thought to number in the billions in our galaxy. In a new study, astronomers argue that these three rapid rotators could be approaching a spin speed limit for all brown dwarfs, beyond which they would break apart. The rapidly rotating brown dwarfs are all about the same diameter as Jupiter but between 40 and 70 times more massive. They each rotate about once per hour, while the next-fastest known brown dwarfs rotate about once every 1.4 hours and Jupiter spins once every 10 hours. Based on their size, that means the largest of the three brown dwarfs whips around at more than 360,000 kilometres per hour). Brown dwarfs, like stars or planets, are already spinning when they form. As they cool down and contract, they spin faster, just like when a spinning ice skater draws her arms into her body. Scientists have measured the spin rates of about 80 brown dwarfs, and they vary from less than two hours (including the three new entries) to tens of hours. With so much variety among the brown dwarf speeds already measured, it surprised the authors of the new study that the three fastest brown dwarfs ever found have almost the exact same spin rate (about one full rotation per hour) as each other. This cannot be attributed to the brown dwarfs having formed together or being at the same stage in their development, because they are physically different: One is a warm brown dwarf, one is cold, and the other falls between them. Since brown dwarfs cool as they age, the temperature differences suggest these brown dwarfs are different ages.

The authors aren't chalking this up to coincidence. They think the members of the speedy trio have all reached a spin speed limit, beyond which a brown dwarf could break apart. All rotating objects generate centripetal force, which increases the faster the object spins. On a carnival ride, this force can threaten to throw riders from their seats; in stars and planets, it can tear the object apart. Before a spinning object breaks apart, it will often start bulging around its midsection as it deforms under the pressure. Scientists call this oblation. Saturn, which rotates once every 10 hours like Jupiter, has a perceptible oblation. Based on the known characteristics of the brown dwarfs, they likely have similar degrees of oblation, according to the paper authors. Considering that brown dwarfs tend to speed up as they age, are these objects regularly exceeding their spin speed limit and being torn apart? In other rotating cosmic objects, like stars, there are there natural braking mechanisms that stop them from destroying themselves. It's not clear yet if similar mechanisms exist in brown dwarfs. The maximum spin rate of any object is determined not only by its total mass but by how that mass is distributed. That's why, when very rapid spin rates are involved, understanding a brown dwarf's interior structure becomes increasingly important: The material inside likely shifts and deforms in ways that could change how fast the object can spin. Similar to gas planets such as Jupiter and Saturn, brown dwarfs are composed mostly of hydrogen and helium. But they are also significantly denser than most giant planets. Scientists think the hydrogen in the core of a brown dwarf is under such tremendous pressures that it starts behaving like a metal rather than an inert gas: It has free-floating conducting electrons, much like a copper conductor. That changes how heat is conducted through the interior and with very fast spin rates, may also affect how the mass inside an astronomical object is distributed. Physicists use observations, laboratory data, and mathematics to create models of what brown dwarf interiors should look like and how they should behave, even under extreme conditions. But current models show that the maximum brown dwarf spin speed should be about 50% to 80% faster than the one-hour rotation period described in the new study. It is possible that these theories don't have the full picture yet. Some unappreciated factor may be coming into play that doesn't let the brown dwarf spin faster. Additional observations and theoretical work may yet reveal whether there's some braking mechanism that stops brown dwarfs from self-destruction and whether there are brown dwarfs spinning even faster in the darkness.

DOUBLE QUASARS IN MERGING GALAXIES
NASA/Goddard Space Flight Center

Hubble astronomers found a pair of quasars that are so close to each other they look like a single object in ground-based telescopic photos. The researchers believe the quasars are very close to each other because they reside in the cores of two merging galaxies. A quasar is a brilliant beacon of intense light from the centre of a distant galaxy that can outshine the entire galaxy. It is powered by a supermassive black hole voraciously feeding on inflating matter, unleashing a torrent of radiation. It is estimated that in the distant Universe, for every 1,000 quasars, there is one double quasar. Quasars are scattered all across the sky and were most abundant 10 billion years ago. There were a lot of galaxy mergers back then feeding the black holes. Therefore, astronomers theorize there should have been many dual quasars during that time. The observations are important because a quasar's role in galactic encounters plays a critical part in galaxy formation, the researchers say. As two close galaxies begin to distort each other gravitationally, their interaction funnels material into their respective black holes, igniting their quasars. Over time, radiation from these high-intensity "light bulbs" launch powerful galactic winds, which sweep out most of the gas from the merging galaxies. Deprived of gas, star formation ceases, and the galaxies evolve into elliptical galaxies. Astronomers have discovered more than 100 double quasars in merging galaxies so far. However, none of them is as old as the two double quasars in this study. The Hubble images show that quasars within each pair are only about 10,000 light-years apart. By comparison, our Sun is 26,000 light-years from the supermassive black hole in the centre of our galaxy. The pairs of host galaxies will eventually merge, and then the quasars also will coalesce, resulting in an even more massive, single solitary black hole.

Astronomers first needed to figure out where to point Hubble to study them. The challenge is that the sky is blanketed with a tapestry of ancient quasars that flared to life 10 billion years ago, only a tiny fraction of which are dual. It took an imaginative and innovative technique that required the help of the European Space Agency's Gaia satellite and the ground-based Sloan Digital Sky Survey to compile a group of potential candidates for Hubble to observe. The researchers then enlisted the Gaia observatory to help pinpoint potential double-quasar candidates. Gaia measures the positions, distances, and motions of nearby celestial objects very precisely. But the team devised a new, innovative application for Gaia that could be used for exploring the distant Universe. They used the observatory's database to search for quasars that mimic the apparent motion of nearby stars. The quasars appear as single objects in the Gaia data. However, Gaia can pick up a subtle, unexpected "jiggle" in the apparent position of some of the quasars it observes. The quasars aren't moving through space in any measurable way, but instead their jiggle could be evidence of random fluctuations of light as each member of the quasar pair varies in brightness. Quasars flicker in brightness on timescales of days to months, depending on their black hole's feeding schedule. This alternating brightness between the quasar pair is similar to seeing a railroad crossing signal from a distance. As the lights on both sides of the stationary signal alternately flash, the sign gives the illusion of "jiggling." When the first four targets were observed with Hubble, it revealed that two of the targets are two close pairs of quasars. Although the team is convinced of their result, they say there is a slight chance that the Hubble snapshots captured double images of the same quasar, an illusion caused by gravitational lensing. This phenomenon occurs when the gravity of a massive foreground galaxy splits and amplifies the light from the background quasar into two mirror images. However, the researchers think this scenario is highly unlikely because Hubble did not detect any foreground galaxies near the two quasar pairs. Galactic mergers were more plentiful billions of years ago, but a few are still happening today. One example is NGC 6240, a nearby system of merging galaxies that has two and possibly even three supermassive black holes. An even closer galactic merger will occur in a few billion years when our Milky Way galaxy collides with neighbouring Andromeda galaxy. The galactic tussle would likely feed the supermassive black holes in the core of each galaxy, igniting them as quasars.

CARBON'S INTERSTELLAR JOURNEY TO EARTH
University of Michigan

We are made of stardust, the saying goes, and a pair of studies finds that may be more true than we previously thought. The first study finds that most of the carbon on Earth was likely delivered from the interstellar medium, the material that exists in space between stars in a galaxy. This likely happened well after the protoplanetary disk, the cloud of dust and gas that circled our young Sun and contained the building blocks of the planets, formed and warmed up. Carbon was also likely sequestered into solids within one million years of the Sun's birth -- which means that carbon, the backbone of life on Earth, survived an interstellar journey to our planet.

Previously, researchers thought carbon in the Earth came from molecules that were initially present in nebular gas, which then accreted into a rocky planet when the gases were cool enough for the molecules to precipitate. Astronomers point out in this study that the gas molecules that carry carbon wouldn't be available to build the Earth because once carbon vaporizes, it does not condense back into a solid. Much of carbon was delivered to the disk in the form of organic molecules. Because of this, the team inferred most of Earth's carbon was likely inherited directly from the interstellar medium, avoiding vaporization entirely. To better understand how Earth acquired its carbon, astronomers estimated the maximum amount of carbon Earth could contain. To do this, they compared how quickly a seismic wave travels through the core to the known sound velocities of the core. This told the researchers that carbon likely makes up less than half a percent of Earth's mass. Understanding the upper bounds of how much carbon the Earth might contain tells the researchers information about when the carbon might have been delivered here. A planet's carbon must exist in the right proportion to support life as we know it. Too much carbon, and the Earth's atmosphere would be like Venus, trapping heat from the Sun and maintaining a temperature of about 880 degrees Fahrenheit. Too little carbon, and Earth would resemble Mars: an inhospitable place unable to support water-based life, with temperatures around minus 60.

In a second study by the same group of authors looked at how carbon is processed when the small precursors of planets, known as planetesimals, retain carbon during their early formation. By examining the metallic cores of these bodies, now preserved as iron meteorites, they found that during this key step of planetary origin, much of the carbon must be lost as the planetesimals melt, form cores and lose gas. This upends previous thinking. Most models have the carbon and other life-essential materials such as water and nitrogen going from the nebula into primitive rocky bodies, and these are then delivered to growing planets such as Earth or Mars. But this skips a key step, in which the planetesimals lose much of their carbon before they accrete to the planets. The two studies both describe two different aspects of carbon loss -- and suggest that carbon loss appears to be a central aspect in constructing the Earth as a habitable planet. Answering whether or not Earth-like planets exist elsewhere can only be achieved by working at the intersection of disciplines like astronomy and geochemistry. Over the history of our galaxy alone, rocky planets like the Earth or a bit larger have been assembled hundreds of millions of times around stars like the Sun. Can we extend this work to examine carbon loss in planetary systems more broadly? Such research will take a diverse community of scholars.

DOUBT CAST OVER 70% OF UNIVERSE COMPOSITION :
University of Copenhagen - Faculty of Science

Until now, researchers have believed that dark energy accounted for nearly 70 percent of the ever-accelerating, expanding Universe. For many years, this mechanism has been associated with the so-called cosmological constant, developed by Einstein in 1917, that refers to an unknown repellent cosmic power. But because the cosmological constant -- known as dark energy -- cannot be measured directly, numerous researchers, including Einstein, have doubted its existence -- without being able to suggest a viable alternative. In a new study a model was tested that replaces dark energy with a dark matter in the form of magnetic forces. The usual understanding of how the Universe's energy is distributed is that it consists of five percent normal matter, 25 percent dark matter and 70 percent dark energy. In the new model, the 25 percent share of dark matter is accorded special qualities that make the 70 percent of dark energy redundant. We don't know much about dark matter other than that it is a heavy and slow particle. But then researchers wondered -- what if dark matter had some quality that was analogous to magnetism in it? We know that as normal particles move around, they create magnetism. And, magnets attract or repel other magnets -- so what if that's what's going on in the Universe? That this constant expansion of dark matter is occurring thanks to some sort of magnetic force?

The question served as the foundation for the new computer model, where researchers included everything that they know about the Universe -- including gravity, the speed of the Universe's expansion and X, the unknown force that expands the Universe. They developed a model that worked from the assumption that dark matter particles have a type of magnetic force and investigated what effect this force would have on the Universe. It turns out that it would have exactly the same effect on the speed of the Universe's expansion as we know from dark energy. However, there remains much about this mechanism that has yet to be understood by the researchers. And it all needs to be checked in better models that take more factors into consideration. The team says the discovery may just be a coincidence. But if it isn't, it is truly incredible. It would change our understanding of the universe's composition and why it is expanding. As far as our current knowledge, our ideas about dark matter with a type of magnetic force and the idea about dark energy are equally wild. Only more detailed observations will determine which of these models is the more realistic.


Bulletin compiled by Clive Down

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