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Topics - Geoffw

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Family History / Forces War Records
February 15, 2020, 10:01:47 am
David talked about this issue at the last meeting.  I wonder if he has come across this website:

https://www.forces-war-records.co.uk/
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Architecture / Giant dams enclosing North Sea
February 12, 2020, 10:12:37 pm
Giant dams enclosing North Sea could protect millions from rising waters

https://www.theguardian.com/environment/2020/feb/12/giant-dams-could-protect-millions-from-rising-north-sea?

Capture.JPG
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 508 2020 February 9
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 https://www.popastro.com/

OLDEST ASTEROID IMPACT MAY HAVE ENDED ICE AGE BBC Science

Scientists have identified the world's oldest asteroid crater in Australia, adding it may explain how the planet was lifted from an ice age. The asteroid hit Yarrabubba in Western Australia about 2.2 billion years ago -- making the crater about half the age of Earth. Their conclusion was reached by testing minerals found in rocks at the site. The scientists say that the find is exciting because it could account for a warming event during that era. The crater was discovered in the dry outback in 1979, but geologists had not previously tested how old it was. To determine when the asteroid hit Earth, the team examined tiny zircon and monazite crystals in the rocks.  They were 'shocked' in the strike and now can be read like tree rings.  These crystals hold tiny amounts of uranium. Because uranium decays into lead at a consistent pace, the researchers were able to calculate how much time had passed. It is at least 200 million years older than the next most ancient impact structure -- the Vredefort Dome in South Africa. The timing of the impact could also explain why the world warmed around this time, according to the researchers. Scientists believe the planet was previously in one of its "Snowball Earth" periods, when it was largely covered in ice. At some point, the ice sheets melted and the planet began rapidly to
warm. Using computer modelling, the team calculated that the asteroid struck a kilometres-thick ice sheet covering the Earth. The event would have released huge volumes of water vapour, a greenhouse gas, into the atmosphere. This could have helped the planet's warming during the
Proterozoic era -- a stage when oxygen had just appeared in the atmosphere and complex life had not yet formed. There is not enough modelling from the time to test the theory comprehensively, but "the rocks tell a story about the massive impact onto the planet". Another theory for the warming event is that volcanic eruptions may have pushed carbon dioxide into the
atmosphere.

MARS' WATER WAS MINERAL-RICH AND SALTY Tokyo Institute of Technology

Presently, Earth is the only known location where life exists in the Universe. This year the Nobel Prize in physics was awarded to three astronomers who proved, almost 20 years ago, that planets are common around stars beyond the solar system. Life comes in various forms, from organisms like humans to the ubiquitous micro-organisms that inhabit almost every square inch of the planet Earth, affecting almost everything that happens on it. It will probably be some time before it is possible to measure or detect life beyond the solar system, but the solar system offers a host of sites that might get a handle on how hard it is for life to start. Mars is at the
top of this list for two reasons. First, it is relatively close to Earth compared to the moons of Saturn and Jupiter (which are also considered good candidates for discovering life beyond Earth in the solar system, and are targeted for exploration in the coming decade). Secondly, Mars is extremely observable because it lacks a thick atmosphere like Venus, and so far, there is pretty good evidence that Mars' surface temperature and pressure hover around the point where liquid water -- considered essential for life -- can exist. Further, there is good evidence in the form of observable river deltas, and more recent measurements made on Mars' surface, that liquid
water did in fact flow on Mars billions of years ago. Scientists are becoming increasingly convinced that billions of years ago Mars was habitable. Whether it was in fact inhabited, or is still inhabited, remains hotly debated. To constrain these questions better, scientists are trying to
understand the kinds of water chemistry that could have generated the minerals observed on Mars today, which were produced billions of years ago.

Salinity (how much salt was present), pH (a measure of how acidic the water was), and redox state (roughly a measure of the abundance of gases such as hydrogen [H2, which are termed reducing environments] or oxygen [O2, which are termed oxidising environments; the two types are generally mutually incompatible]) are fundamental properties of natural waters. As an example, Earth's modern atmosphere is highly oxygenated (containing large amounts of O2), but one need only dig a few inches into the bottom of a beach or lake today on Earth to find environments which are highly reduced. Recent remote measurements on Mars suggest its ancient environments may provide clues about Mars' early habitability. Specifically, the properties of pore water within sediments apparently deposited in lakes in Gale Crater on Mars
suggest these sediments formed in the presence of liquid water which was of a pH close to that of Earth's modern oceans. Earth's oceans are of course host to myriad forms of life, thus it seems compelling that Mars' early surface environment was a place where contemporary Earth life could have lived,but it remains a mystery as to why evidence of life on Mars is so hard to find.

HOTTEST PLANET IN MAJOR MELTDOWN NASA
Massive gas giants called 'hot Jupiters' -- planets that orbit too close to their stars to sustain life -- are some of the strangest worlds found beyond our solar system. New observations show that the hottest of them all is stranger still, prone to planet-wide meltdowns so severe they tear apart the molecules that make up its atmosphere. Called KELT-9b, the planet is an ultra-hot Jupiter, one of several varieties of exoplanets -- planets around other stars -- found in our galaxy. It weighs in at nearly three times the mass of our own Jupiter and orbits a star some 670 light-years away. With a surface temperature of 4,300 degrees Celsius - hotter than some stars - this
planet is the hottest found so far. Now, a team of astronomers using NASA's Spitzer space telescope has found evidence that the heat is too much even for molecules to remain intact. Molecules of hydrogen gas are likely ripped apart on the dayside of KELT-9b, unable to re-form until their disjointed atoms flow around to the planet's nightside. Though still extremely hot, the night-side's slight cooling is enough to allow hydrogen gas molecules to reform -- that is, until they flow back to the dayside, where they're torn apart all over again. KELT-9b will stay firmly categorized among the uninhabitable worlds. Astronomers became aware of its extremely hostile
environment in 2017, when it was first detected using the Kilodegree Extremely Little Telescope (KELT) system -- a combined effort involving observations from two robotic telescopes, one in southern Arizona and one in South Africa.

The science team used the Spitzer space telescope to obtain temperature profiles from this infernal giant. Spitzer, which makes observations in infrared light, can measure subtle variations in heat. Repeated over many hours, these observations allow Spitzer to capture changes in the atmosphere as the planet presents itself in phases while orbiting the star. Different halves of the planet roll into view as it orbits around its star. That allowed the team to catch a glimpse of the difference between KELT-9b's dayside and its "night". In this case, the planet orbits its star so tightly that a "year" - once around the star - takes only 1 1/2 days. That means the planet is tidally locked, presenting one face to its star for all time (as our Moon presents only one face to Earth). On the far side of KELT-9b, nighttime lasts forever. But gases and heat flow from one side to the other. A big question for researchers trying to understand exoplanet atmospheres is how radiation and flow balance each other out. Computer models are major tools in such investigations, showing how these atmospheres are likely to behave in different temperatures. The best fit for the data from KELT-9b was a model that included hydrogen molecules being torn apart and reassembled, a process known as dissociation and recombination. KELT-9b turns out not to have huge temperature differences between its day- and night-sides, suggesting heat flow from one to the other. And the "hot spot" on the dayside, which is supposed to be directly under this planet's star, was shifted away from its expected position. Scientists don't know why - yet another mystery to be solved on this strange, hot planet.

LARGE AMOUNTS OF OXYGEN IN ANCIENT STAR  W. M. Keck Observatory
Astronomers have detected large amounts of oxygen in the atmosphere of one of the oldest and most elementally depleted stars known -- a "primitive star" scientists call J0815+4729. This new finding, which was made using W. M. Keck Observatory on Mauna Kea in Hawaii to analyze the chemical makeup of the ancient star, provides an important clue on how oxygen and other
important elements were produced in the first generations of stars in the universe. Oxygen is the third most abundant element in the universe after hydrogen and helium, and is essential for all forms of life on Earth, as the chemical basis of respiration and a building block of carbohydrates. It is also the main elemental component of the Earth's crust. However, oxygen didn't exist in the early universe; it is created through nuclear fusion reactions that occur deep inside the most massive stars, those with masses roughly 10 times the mass of the Sun or greater. Tracing the early production of oxygen and other elements requires studying the oldest stars still in existence. J0815+4729 is one such star; it resides over 5,000 light-years away toward the constellation Lynx. Stars like J0815+4729 are referred to as halo stars owing to their roughly spherical distribution around the Milky Way, as opposed to the more familiar flat disk of younger
stars that include the Sun. Halo stars like J0815+4729 are truly ancient stars, allowing astronomers a peek into element production early in the history of the universe. The research team observed J0815+4729 using Keck Observatory's High-Resolution Echelle Spectrometer (HIRES) on the 10m Keck I telescope. The data, which required more than five hours of staring at the star over a single night, were used to measure the abundances of 16 chemical species in the star's atmosphere, including oxygen.

Keck Observatory's HIRES data of the star revealed a very unusual chemical composition. While it has relatively large amounts of carbon, nitrogen, and oxygen -- approximately 10, 8, and 3 percent of the abundances measured in the Sun -- other elements like calcium and iron have abundances around one millionth that of the Sun. Only a few such stars are known in the halo of
our galaxy, but none has such an enormous amount of carbon, nitrogen, and oxygen compared to their iron content. The search for stars of this type involves dedicated projects that sift through hundreds of thousands of stellar spectra to uncover a few rare sources like J0815+4729, then
follow-up observations to measure their chemical composition. This star was first identified in data obtained with the Sloan Digital Sky Survey (SDSS), then characterized by the IAC team in 2017 using the Grand Canary Telescope in La Palma, Spain.


WEBB TELESCOPE WILL CONTINUE SPITZER'S LEGACY NASA
As one window to the universe closes, another will open with an even better view. Some of the same planets, stars and galaxies we first saw through the first window will appear in even sharper detail in the one that will soon open. NASA's Spitzer Space Telescope concluded its mission on Jan. 30, 2020, after more than 16 extraordinary years of exploration. The telescope
has made many discoveries beyond the imaginations of its designers, such as planets outside our solar system, called exoplanets, and galaxies that formed close to the beginning of the universe. Many of Spitzer's break-throughs will be studied more precisely with the forthcoming James Webb Space Telescope, which is expected to be launched next year. Both Webb and
Spitzer are specialized for infrared light, which is invisible to human eyes. But with its giant gold-coated beryllium mirror and nine new technologies, Webb is about 1,000 times more powerful. The forthcoming telescope will be able to push Spitzer's science findings to new frontiers,
from identifying chemicals in exoplanet atmospheres to locating some of the first galaxies to form after the Big Bang. Beyond its discoveries, Spitzer is also a pathfinder for Webb in terms of how to operate a telescope of this kind. In order to measure infrared light with high sensitivity, a telescope must be very cold. Spitzer has shown engineers how an infrared observatory behaves in the vastness of space and what temperatures mission planners should expect to grapple with for Webb. With more than 8,700 scientific papers published based on Spitzer's discoveries, the telescope has been a tremendous asset to astronomers across a variety of disciplines. Many of
these tantalizing results are ripe for revisiting with a more powerful telescope, and Webb is poised to begin looking into them early in its mission. One of Spitzer's most stunning discoveries was that there are not just three, but seven rocky Earth-size planets orbiting a small, faint star
called TRAPPIST-1. TRAPPIST-1 is one of the best-studied planetary systems apart from our own, but there is a lot more to learn about it. The fourth planet from the star, TRAPPIST-1e is especially interesting because it has a density and surface gravity very similar to Earth's and receives enough stellar radiation to have temperatures friendly enough for liquid water.  Webb will observe this planet to get a better sense of whether the planet has an atmosphere and, if so, what its chemistry is. The presence of molecules such as carbon dioxide, dominant on Mars and Venus, would have implications for whether a planet could have liquid water and other habitable conditions. Webb will be able to detect atmospheric water, too.  Additionally, Webb will search for heat coming from TRAPPIST-1b, the planet closest to its star.

WASP-18b is another intriguing planet that Spitzer examined and that Webb will investigate further in observations early in the mission. This gas giant, with 10 times the mass of Jupiter, is located extremely close to its star, completing an orbit once every 23 hours. Because of its high
temperature - a whopping 2,650 degrees Celsius - and large size, it is known as a "hot Jupiter". Using data from Spitzer and Hubble, astronomers figured out in 2017 that this planet has a lot of carbon monoxide in its upper atmosphere, and little water vapour. The planet is particularly interesting because it's so close to its star that it's in danger of being torn apart completely, and it may not survive another million years. Astronomers are interested in using Webb to look at the processes happening in this planet's atmosphere, which will provide insights into hot Jupiters in general. As light travels from distant objects to Earth, its wavelength becomes longer because the universe is expanding and those objects are moving farther from us. That means that stars that give off visible light in the early universe will appear in the infrared by the time their light reaches Earth. This makes infrared light an especially powerful tool for exploring the universe's ancient past. Pinpointing hundreds of billions of galaxies is currently impossible, but Spitzer has made large galaxy catalogs that represent different slices of the universe, containing some of the most distant galaxies we know. The large survey areas of Spitzer and Hubble Space Telescope have allowed astronomers to look efficiently for objects that could be studied in further detail with Webb. For example, Spitzer, together with Hubble, took an image of a galaxy called GN-z11, which holds the record for most distant galaxy measured yet. It is a relic from when the universe
was only 400 million years old, just 3% of its current age and less than 10% of its size today. What's more, Webb's higher sensitivity will allow the telescope to look for galaxies dating back even earlier in the universe.  And questions still abound about these distant galaxies: Are there a lot of stars forming in them or relatively few? Are they rich in gas or poor? Are there black holes at their centres, and how do those black holes interact with stars? And scientists have pondered a chicken-and-egg problem for decades about which came first: the black hole or the surrounding galaxy?

Bulletin compiled by Clive Down (c) 2020 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 £22 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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Astronomy Group / The Night Sky in February
February 03, 2020, 02:39:26 pm



Whatever the temperature in your part of the world, when the weather allows, head outside with a telescope or pair of binoculars because February is always a great month for stargazing. The bright and rich constellations Orion, Canis Major, Taurus, and Auriga dominate the northern sky this month.  There are also five bright planets to see this month, a major lunar-planetary occultation, and a chance to glimpse the glow of the zodiacal light. Here's what to see in the night sky this month.

The latter part of the month lends itself to dark sky observing

February 5th- evening: The Moon above Orion's weapon

Saturday night the 8th February. The Moon's orbit around Earth is elliptical, with one side closer to Earth than the other. As a result, the distance between the Moon and Earth varies throughout the month and the year. On average, the distance is about 382,900 kilometers (238,000 miles) from the Moon's center to the center of Earth.  The point on the Moon's orbit closest to Earth is called the perigee and the point farthest away is the apogee.  A Full moon at Perigee appears 30% brighter and 1 4% larger than an apogee full moon.

10th February
:  Mercury reaches greatest eastern elongation at 18.2o from the Sun. Just a couple of fist-widths above the western horizon about a half-hour after sunset, it's far lower than Venus but still respectably bright at magnitude 0.0. In a telescope, the disk of Mercury is tiny, just 7" wide, and exactly half lit on this day.

February 18th - before Dawn: a thin crescent Moon lies just to the right of Mars. This could be a nice photo opportunity.

After sunset on the 27th, and given a low horizon towards the west, you may be able to spot a very thin crescent Moon lying down to the lower left of Venus.

February 29th - before Dawn: a line up of Saturn, Jupiter and Mars.

If clear around 6:30 am on the 29th, one will see a nice line up of, from left to right, Saturn, Jupiter and Mars.  A low horizon towards the southeast will be needed to spot Saturn.
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....and a chance to find Neptune if you have your telescope out!
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Architecture / The Art of Building
January 27, 2020, 01:39:19 pm


After thousands of public votes, the winners of the Art of Building Photographer of the Year 2019 have been announced.

The competition, run by the Chartered Institute of Building (CIOB), celebrates the creativity of the construction industry and the built world around us.

To see the rest of the winners CLICK HERE
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General Chatty Stuff / Bought for my grand daughter
January 27, 2020, 09:21:04 am
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 507 2020 January 26

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/

METEORITE CONTAINS 7 BILLION YEAR OLD DUST
Field Museum

Stars have life cycles. They're born when bits of dust and gas floating through space find each other and collapse in on each other and heat up. They burn for millions to billions of years, and then they die. When they die, they pitch the particles that formed in their winds out into space, and those bits of stardust eventually form new stars, along with new planets and moons and meteorites. And in a meteorite that fell fifty years ago in Australia, scientists have now discovered stardust that formed 5 to 7 billion years ago -- the oldest solid material ever found
on Earth. The materials that have been examined are called presolar grains-minerals formed before the Sun was born. These bits of stardust became trapped in meteorites where they remained unchanged for billions of years, making them time capsules of the time before the solar system. But presolar grains are hard to come by. They're rare, found only in about five percent of meteorites that have fallen to Earth, and they're tiny -a hundred of the biggest ones would fit on the period at the end of this sentence. But the Field Museum has the largest portion of the Murchison meteorite, a treasure trove of presolar grains that fell in Australia in
1969. Presolar grains for this study were isolated from the Murchison meteorite for this study about 30 years ago at the University of Chicago. Once the presolar grains were isolated, the researchers figured out from what types of stars they came and how old they were.
The researchers learned that some of the presolar grains in their sample were the oldest ever discovered-based on how many cosmic rays they'd soaked up, most of the grains had to be 4.6 to 4.9 billion years old, and some grains were even older than 5.5 billion years. For context, our Sun is 4.6 billion years old, and Earth is 4.5 billion. But the age of the presolar grains wasn't the end of the discovery.  Since presolar grains are formed when a star dies, they can tell us about the history of stars. And 7 billion years ago, there was apparently a bumper crop of new stars forming-a sort of stellar baby boom. Scientists hypothesize that the
majority of those grains, which are 4.9 to 4.6 billion years old, formed in an episode of enhanced star formation. There was a time before the start of the Solar System when more stars formed than normal. This finding is ammo in a debate between scientists about whether or not new stars form at a steady rate, or if there are highs and lows in the number of new stars over time. Some people think that the star formation rate of the galaxy is constant but thanks to these grains, we now have direct evidence for a period of enhanced star formation in our galaxy seven billion years ago with samples from meteorites.
 
OUTBOUND COMETS LIKELY TO BE ALIEN ORIGIN
National Institutes of Natural Sciences

Astronomers at the National Astronomical Observatory of Japan (NAOJ) have analyzed the paths of two objects heading out of the Solar System forever and determined that they also most likely originated from outside of the Solar System.  These results improve our understanding of the outer Solar System and beyond.  Not all comets follow closed orbits around the Sun. Some fly through the Solar System at high speed before heading out to interstellar space, never to return.  Although it is simple to calculate where these comets are going, determining where they came from is more difficult. There are two possible scenarios. In the first scenario, a comet is originally in a stable orbit far from the Sun, but gravitational interactions with a passing object pull the comet out of its orbit. The comet then falls into the inner Solar System where it can be observed before being flung out into interstellar space. In the second scenario, a comet originates someplace very far away, perhaps a different planetary system, and as it flies through interstellar space, by random chance it passes through the Solar System once before continuing on its way. Astronomers calculated the types of trajectories which would typically be expected in each scenario. The team then compared their calculations to observations of two unusual outbound objects, 1I/'Oumuamua discovered in 2017 and 2I/Borisov discovered in 2019. They found that the interstellar origin scenario provides the better match for the paths of both objects. The team also showed that it is possible for gas-giant-sized bodies passing close to the Solar System to destabilize long-orbit comets and set them on paths similar to the paths of these two objects. Survey observations have not uncovered any gas-giant-sized bodies which can be linked to these two outbound
objects, but further study, both theoretical and observational, of small interstellar objects is needed to better determine the origins of these objects.
 
TESS FINDS EARTH-SIZE PLANET
NASA

The Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size planet in its star's habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on the surface. Scientists confirmed the find, called TOI 700 d, using NASA's Spitzer Space Telescope and have modelled the planet's potential environments to help inform future observations. TOI 700 d is one of only a few Earth-size planets discovered in a star's habitable zone so far. Others include several planets in the TRAPPIST-1 system and other worlds discovered by the Kepler Space Telescope. Discovering TOI 700 d is a key science finding for TESS. Confirming the planet's size and habitable zone status with Spitzer is another win for Spitzer as it approaches the end of science operations this January. TESS monitors large swaths of the sky, called sectors, for 27 days at a time. This long stare allows the satellite to track changes in stellar brightness caused by an orbiting planet crossing in front of its star from our perspective, an event called a transit. TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It's roughly 40% of the Sun's mass and size and about half its surface temperature. The star appears in 11 of the 13 sectors TESS observed during the mission's first year, and scientists caught multiple transits by its three planets. The star was originally misclassified in the TESS database as being more similar to our Sun, which meant the planets appeared larger and hotter than they really are. Several researchers, including Alton Spencer, a high school student working with members of the TESS team, identified the error.

The innermost planet, called TOI 700 b, is almost exactly Earth-size, is probably rocky and completes an orbit every 10 days. The middle planet, TOI 700 c, is 2.6 times larger than Earth - between the sizes of Earth and Neptune - orbits every 16 days and is likely a gas-dominated world. TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20% larger than Earth, orbits every 37 days and receives from its star 86% of the energy that the Sun provides to Earth. All of the planets are thought to be tidally locked to their star, which means they rotate once per orbit so that one side is constantly bathed
in daylight. The Spitzer data increased scientists' confidence that TOI 700 d is a real planet and sharpened their measurements of its orbital period by 56% and its size by 38%. It also ruled out other possible astrophysical causes of the transit signal, such as the presence of a smaller, dimmer companion star in the system.  The team also used follow-up observations from a 1-metre ground-based telescope in the global Las Cumbres Observatory network to improve scientists' confidence in the orbital period and size of TOI 700 c by 30% and 36%,
respectively. Because TOI 700 is bright, nearby, and shows no sign of stellar flares, the system is a prime candidate for precise mass measurements by current ground-based observatories. These measurements could confirm scientists' estimates that the inner and outer planets are rocky and the middle planet is made of gas. Future missions may be able to identify whether the planets have atmospheres and, if so, even determine their compositions. While the exact conditions on TOI 700 d are unknown, scientists can use current information, like the planet's size and the type of star it orbits, to generate computer models and make predictions. Researchers at NASA's Goddard Space Flight Center in Greenbelt, Maryland, modelled 20 potential environments of TOI 700 d to gauge if any version would result in surface temperatures and pressures suitable for habitability.

STRANGE OBJECTS NEAR GALACTIC CENTRE
University of California - Los Angeles

Astronomers from UCLA's Galactic Center Orbits Initiative have discovered a new class of bizarre objects at the centre of our galaxy, not far from the supermassive black hole called Sagittarius A*. The new objects look compact most of the time and stretch out when their orbits bring them closest to the black hole. Their orbits range from about 100 to 1,000 years. The research group identified an unusual object at the centre of our galaxy in 2005, which was later named G1. In 2012, astronomers in Germany made a puzzling discovery of a bizarre object named G2 in the centre of the Milky Way that made a close approach to the supermassive black hole in 2014. The team believe that G2 is most likely two stars that had been orbiting the black hole in tandem and merged into an extremely large star, cloaked in unusually thick gas and dust. At the time of closest approach, G2 had a really strange signature. It had been seen before, but it didn't look too peculiar until it got close to the black hole and became elongated, and much of its gas was torn apart. It went from being a pretty
innocuous object when it was far from the black hole to one that was really stretched out and distorted at its closest approach and lost its outer shell, and now it's getting more compact again. What has made everyone excited about the G objects is that the stuff that gets pulled off of them by tidal forces as they sweep by the central black hole must inevitably fall into the black hole. When that happens, it might be able to produce an impressive fireworks show since the material eaten by the black hole will heat up and emit copious radiation before it disappears across the event horizon. But are G2 and G1 outliers, or are they part of a larger
class of objects? In answer to that question, the research group reports the existence of four more objects they are calling G3, G4, G5 and G6. The researchers have determined each of their orbits. While G1 and G2 have similar orbits, the four new objects have very different orbits.
The team believes all six objects were binary stars -- a system of two stars orbiting each other -- that merged because of the strong gravitational force of the supermassive black hole. The merging of two stars takes more than 1 million years to complete. Mergers of stars may be happening in the universe more often than we thought, and likely are quite common. Black holes may be driving binary stars to merge. It's possible that many of the stars we've been watching and not understanding may be the end product of mergers that are calm now. We are
learning how galaxies and black holes evolve. The way binary stars interact with each other and with the black hole is very different from how single stars interact with other single stars and with the black hole. The team noted that while the gas from G2's outer shell got stretched dramatically, its dust inside the gas did not get stretched much. Something must have kept it compact and enabled it to survive its encounter with the black hole. This is evidence for a stellar object inside G2. In September 2019, the team reported that the black hole is getting hungrier and it is unclear why. The stretching of G2 in 2014 appeared to pull off gas that may
recently have been swallowed by the black hole. The team has already identified a few other candidates that may be part of this new class of objects, and are continuing to analyze them.

STRIPPED HELIUM STAR SOLVES MASSIVE BLACK HOLE MYSTERY
University of Erlangen-Nuremberg

Stellar black holes form when massive stars end their life in a dramatic collapse. Observations have shown that stellar black holes typically have masses of about ten times that of the Sun, in accordance with the theory of stellar evolution.  Recently, a Chinese team of astronomers claimed to have discovered a black hole as massive as 70 solar masses, which, if confirmed, would severely challenge the current view of stellar evolution. The publication immediately triggered theoretical investigations as well as additional observations by other astrophysicists. Among those to take a closer look at the object was a team of astronomers from the
Universities of Erlangen-Nürnberg and Potsdam. They discovered that it may not necessarily be a black hole at all, but possibly a massive neutron star or even an 'ordinary' star. The putative black hole was detected indirectly from the motion of a bright companion star, orbiting an invisible compact object over a period of about 80 days. From new observations, a Belgian team showed that the original measurements were misinterpreted and that the mass of the black hole is, in fact, very uncertain. The most important question, namely how the observed binary system was created, remains unanswered. A crucial aspect is the mass of the visible companion, the hot star LS V+22 25. The more massive this star is, the more massive the black hole has to be to induce the observed motion of the bright star. The latter was considered to be a normal star, eight times more massive than the Sun. A team of astronomers from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and the University of Potsdam had a closer look at the archival spectrum of LS V+22 25, taken by the Keck telescope at Mauna Kea, Hawaii. In particular, they were interested in studying the abundances of the chemical elements on the stellar surface. Interestingly, they detected
deviations in the abundances of helium, carbon, nitrogen, and oxygen compared to the standard composition of a young massive star. The observed pattern on the surface showed ashes resulting from the nuclear fusion of hydrogen, a process that only happens deep in the core of young stars and would not be expected to be detected at its surface.
At first glance, the spectrum did indeed look like one from a young massive star.  However, several properties appeared rather suspicious. This motivated the team concluded that LS V+22 25 must have interacted with its compact companion in the past. During this episode of mass-transfer, the outer layers of the star were removed and now the stripped helium core is visible, enriched with the ashes from the burning of hydrogen. However, stripped helium stars are much lighter than their normal counterparts. Combining their results with recent distance
measurements from the Gaia space telescope, the authors determined a most likely stellar mass of only 1.1 (with an uncertainty of +/-0.5) times that of the Sun.  This yields a minimum mass of only 2-3 solar masses for the compact companion, suggesting that it may not necessarily be a black hole at all, but possibly a massive neutron star or even an 'ordinary' star. The star LS V+22 25 has become famous for possibly having a massive black hole companion. However, a closer look at the star itself reveals that it is a very intriguing object in its own right, as whilst stripped helium stars of intermediate mass have been predicted in theory, only very few have been discovered so far. They are key objects to understanding
binary star interactions.
 
THE TEMPERATURE OF DARK MATTER
University of California - Davis

Warm, cold, just right? Physicists at the University of California, Davis are taking the temperature of dark matter, the mysterious substance that makes up about a quarter of our universe. We have very little idea of what dark matter is and physicists have yet to detect a dark matter particle. But we do know that the gravity of clumps of dark matter can distort light from distant objects. Now astronomers are using this distortion, called gravitational lensing, to learn more about the properties of dark matter. The standard model for dark matter is that it
is 'cold,' meaning that the particles move slowly compared to the speed of light.  This is also tied to the mass of dark matter particles. The lower the mass of the particle, the 'warmer' it is and the faster it will move. The model of cold (more massive) dark matter holds at very large scales but doesn't work so well on the scale of individual galaxies. That's led to other models including 'warm' dark matter with lighter, faster-moving particles. 'Hot' dark matter with particles moving close to the speed of light has been ruled out by observations. Astronomers have
used gravitational lensing to put a limit on the warmth and therefore the mass of dark matter. They measured the brightness of seven distant gravitationally lensed quasars to look for changes caused by additional intervening blobs of dark matter and used these results to measure the size of these dark matter lenses. If dark matter particles are lighter, warmer and more rapidly-moving, then they will not form structures below a certain size. Below a certain size, they would just get smeared out. The results put a lower limit on the mass of a potential dark matter particle while not ruling out cold dark matter.
Bulletin compiled by Clive Down
(c) 2020 The Society for Popular Astronomy


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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 506 2020 January 5

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/
 
"ONCE IN A LIFETIME" STRATOSPHERIC CLOUDS
Spaceweather.com

A spectacular outbreak of polar stratospheric clouds (PSCs) is under way around the Arctic Circle. Polar stratospheric clouds are newsworthy because normally the stratosphere has no clouds at all. Home to the ozone layer, the stratosphere is arid and almost always transparent. Only when the temperature drops to a staggeringly cold -85C can sparse water molecules
assemble themselves into icy stratospheric clouds. PSCs are far more rare than aurorae. At one point villagers reported that close to 25% of the sky was filled with the clouds. PSCs in previous winters have been closer to 1% or 2%. PSCs are intensely colourful because they are made of a special type of ice. High-altitude sunlight shining through microscopic crystals only ~10 microns across produce a bright iridescent glow unlike the lesser iridescence of ordinary tropospheric clouds.

PLANET AND STAR GIVEN MANX NAMES
BBC Science

A star and planet will be given Manx Gaelic names for the first time after being chosen in an international competition. The star WASP-13 will be known as Gloas (which means 'to shine') and the planet WASP-13b as Cruinlagh ('to orbit'). A class of Manx eight and nine-year-olds came up with the names for a competition run by the International Astronomical Union (IAU).
The names were chosen due to their "sense of mystery" after taking 20% of 15,000 votes cast by members of the public. The naming competition was held by the IAU as part of a larger worldwide event to celebrate its 100th anniversary. More than 110 countries were given an opportunity to name a star and an exoplanet (a planet outside of the solar system), with each
winning entry being rec gnised internationally. WASP-13, a star within the Lynx constellation that was first observed in 1997, is 1.5 times bigger than the Sun and is visible with the naked eye from the British Isles. WASP-13b, which was discovered in 2009, orbits the star every four days and is bigger than Jupiter.

BETELGEUSE NOTICEABLY DIMMER
EarthSky

The red supergiant star Betelgeuse, in the shoulder of the constellation Orion, is one of the easiest-to-recognize stars in the night sky. It is also one of the biggest stars we know, with a radius extending out to the distance of Mars from our Sun, and possibly Jupiter. This star is also famous for the fact that it will someday explode and appear in our sky as a supernova, becoming visible in daytime. In recent weeks astronomers have become excited about the fact that this bright star has become noticeably dimmer and is now well below magnitude 1. Could it be a sign that Betelgeuse is about to explode as a supernova? Astronomers say probably
not. Betelgeuse is normally one of 2 very bright stars in the constellation Orion; the other one is Rigel.

DISTANT MILKY-WAY-LIKE GALAXIES
National Radio Astronomy Observatory
To learn about the star-formation history of the Universe, we need to look back in time. Galaxies throughout the Universe have been forming stars for the past 13 billion years. But most stars were born between 8 and 11 billion years ago, during an era called "cosmic noon". It has been a challenge for astronomers to study the faint light coming from that era. Optical telescopes can see very distant galaxies, but new stars are largely hidden inside dusty clouds of gas. Radio telescopes can see through the dust and observe the rare, bright starburst galaxies, but until now have not been sensitive enough to detect the signals from distant Milky Way-like galaxies that are responsible for most of the star formation in the Universe. An international team of astronomers using the South African Radio Astronomy Observatory (SARAO) MeerKAT telescope recently made the first radio observation sensitive enough to reveal such galaxies. To make the image, they selected an area in the southern sky that contains no strong radio sources whose glare could blind a sensitive observation. The team used the 64 MeerKAT dishes to observe the area for a total of 130 hours. The resulting image shows a region of the sky that is comparable in area to five full Moons, containing tens of thousands of galaxies.
Because radio waves travel at the speed of light, the image is a time machine that samples star formation in those distant galaxies over billions of years. Only short-lived stars that are less than 30 million years old send out radio waves, so astronomers know that the image is not contaminated by old stars. The radio light we see from each galaxy is therefore proportional to its star-forming rate at that moment in time. The astronomers want to use the image to learn more about star formation in the entire Universe. These first results indicate that the star-formation rate around cosmic noon is even higher than was originally expected. Previous
images could only detect the tip of the iceberg, the rare and luminous galaxies that produced only a small fraction of the stars in the Universe.  What can be seen now is the complete picture: these faint dots are the galaxies that formed most of the stars in the Universe.

BLACK HOLES AT THE COSMIC DAWN
ESO

Astronomers using the Very Large Telescope have observed reservoirs of cool gas around some of the earliest galaxies in the Universe. Those gas haloes are the perfect food for supermassive black holes at the centres of those galaxies, which are now seen as they were over 12.5 billion years ago.  This food storage might explain how these cosmic monsters grew so fast during a period in the Universe's history known as the Cosmic Dawn.  Astronomers have wondered how supermassive black holes were able to grow so large so early on in the history of the Universe. The presence of these early monsters, with masses several billion times the mass of our Sun, is a big mystery for astronomers. It means that the first black holes, which might have formed from the collapse of the first stars, must have grown very fast. But, until now, astronomers had not observed black hole food -- gas and dust -- in large enough quantities to explain this rapid growth. To complicate matters further, previous observations with ALMA, the Atacama Large Millimeter/submillimeter Array, revealed a lot of dust and gas in these early galaxies that fuelled rapid star formation. Those ALMA observations suggested that there could be little left over to feed a black
hole.
To solve this mystery, astronomers used the MUSE instrument on the Very Large Telescope (VLT) in the Chilean Atacama Desert to study quasars -- extremely bright objects powered by supermassive black holes which lie at the centre of massive galaxies. The study surveyed 31 quasars that are seen as they were more than 12.5 billion years ago, at a time when the Universe was still an infant, only about 870 million years old. This is one of the largest samples of quasars from so early on in the history of the Universe to be surveyed. The astronomers found that 12 quasars were surrounded by enormous gas reservoirs: haloes of cool, dense hydrogen gas extending 100000 light-years from the central black holes and with billions of times the mass of the Sun. The team also found that the gas haloes were tightly bound to
the galaxies, providing the perfect food source to sustain both the growth of supermassive black holes and vigorous star formation. While quasars are bright, the gas reservoirs around them are much harder to observe. But MUSE could detect the faint glow of the hydrogen gas in the haloes, allowing astronomers finally to reveal the food stashes that power supermassive black holes in the early Universe. In the future, ESO's Extremely Large Telescope (ELT) will help scientists reveal even more details about galaxies and supermassive black holes in the first couple of billion years after the Big Bang.

VIEW OF UNIVERSE UNDER THREAT
BBC Science


A campaign to launch thousands of new satellites has begun in earnest, offering high-speed internet access from space. But the first fleets of these spacecraft, which have already been sent into orbit by US company SpaceX, are affecting images of the night sky. They are appearing as bright white streaks, so dazzling that they are competing with the stars.
Scientists are worried that future "mega-constellations" of satellites could obscure images from optical telescopes and interfere with radio astronomy observations. To give you an idea of the numbers, there are currently just 2,200 active satellites flying around the Earth. But now the Starlink constellation - a project by US company SpaceX - will start sending batches of 60 telescopes into orbit every few weeks. This will mean about 1,500 satellites have been launched by the end of next year, and by the mid-2020s there could be a fleet of 12,000. UK company OneWeb are aiming for about 650 satellites -- but this could rise to 2,000 if there is enough customer demand. Amazon have a constellation of 3,200 spacecraft planned.  These satellites are about the size of a table, but they're very reflective, and their panels reflect lots of the Sun's light, which means that we can see them in images that we take with telescopes.
The satellites are also big radiowave users -- and that means that they can interfere with the signals that astronomers using. So it also affects radio astronomy as well. The satellites could have a real impact on observations, as they present a foreground between what we're observing from the Earth and the rest of the Universe. So they get in the way of everything. It would be particularly troublesome for telescopes taking large surveys of the sky, such as the future Large Synoptic Survey Telescope (LSST) in Chile. For their next launch, SpaceX are trialling a special coating that is designed to make the spacecraft less bright to see if that will help. OneWeb said they wanted to be a "thought leader in responsible space" and were putting
their satellites into an orbit of 1,200km so they would not interfere with astronomical Observations.
Bulletin compiled by Clive Down
(c) 2020 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 £22 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




11
Astronomy Group / Today in Space
January 01, 2020, 04:30:32 pm
New Year's Day

Moon at apogee

1801: Giuseppe Piazzi discovers asteroid Ceres
2019: New Horizons flies by Kuiper Belt Object 2014 MU69 Ultima Thule
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 505 2019 December 22
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/

FIRST IDENTIFIED COMET TO VISIT FROM ANOTHER STAR
NASA/Goddard Space Flight Center

When astronomers see something in the Universe that at first glance seems like one-of-a-kind, it's bound to stir up a lot of excitement and attention.  Enter comet 2I/Borisov. This mysterious visitor from the depths of space is the first identified comet to arrive here from another star. We don't know from where or when the comet started heading toward our Sun, but it won't hang around for long. The Sun's gravity is slightly deflecting its trajectory, but can't capture it because of the shape of its orbit and high velocity of about 100,000 miles per hour. Telescopes around the world have been watching the fleeting visitor. The Hubble Space Telescope has provided the sharpest views as the comet skirts by our Sun. Hubble revealed that the heart of the comet, a loose agglomeration of ices and dust particles, is probably no more than about 3,200 feet across. Though comet Borisov is the first of its kind, no doubt there are many other comet vagabonds out there, plying the space between stars. Astronomers will eagerly be on the lookout for the next mysterious visitor from far beyond. Crimean amateur astronomer Gennady Borisov discovered the comet on 2019 August 30, and reported the position measurements to the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts. The Center for Near-Earth Object Studies
at NASA's Jet Propulsion Laboratory in Pasadena, California, working with the Minor Planet Center, computed an orbit for the comet, which shows that it came from elsewhere in our Milky Way galaxy, point of origin unknown.  Nevertheless, observations by numerous telescopes show that the comet's chemical composition is similar to that of the comets found inside our solar system, providing evidence that comets also form around other stars. By the middle of 2020 the comet will have already zoomed past Jupiter's distance of 500 million miles on its way back into the frozen abyss of interstellar space.

NASA's TREASURE MAP FOR WATER ICE ON MARS
NASA

NASA has big plans for returning astronauts to the Moon in 2024, a stepping stone on the path to sending humans to Mars. But where should the first  people on the Red Planet land? A new paper published in Geophysical Research Letters will help by providing a map of water ice believed to be as little as 2.5 centimetres below the surface. Water ice will be a key consideration for any potential landing site. With little room to spare aboard a spacecraft, any human missions to Mars will have to harvest what's already available for drinking water and making rocket fuel. NASA calls this concept "in situ resource utilization". and it's an important factor  in selecting human landing sites on Mars. Satellites orbiting Mars are
essential in helping scientists determine the best places for building the first Martian research station. The authors of the new paper make use of data from two of those spacecraft, NASA's Mars Reconnaissance Orbiter (MRO) and Mars Odyssey orbiter, to locate water ice that could potentially be within reach of astronauts on the Red Planet.
Liquid water can't last in the thin air of Mars; with so little air pressure, it evaporates from a solid to a gas when exposed to the atmosphere. Martian water ice is locked away underground throughout the planet's mid-latitudes. The regions near the poles have been studied by NASA's Phoenix lander, which scraped up ice, and MRO, which has taken many images from space of meteor impacts that have excavated this ice. To find ice that astronauts could easily dig up, the study's authors relied on two heat-sensitive instruments: MRO's Mars Climate Sounder and the Thermal Emission Imaging System (THEMIS) camera on Mars Odyssey. Why use heat-
sensitive instruments when looking for ice? Buried water ice changes the temperature of the Martian surface. The study's authors cross-referenced temperatures suggestive of ice with other data, such as reservoirs of ice detected by radar or seen after meteor impacts. Data from Odyssey's Gamma Ray Spectrometer, which is tailor-made for mapping water ice deposits, were also useful. As expected, all those data suggest a trove of water ice throughout the Martian poles and mid-latitudes. But the map reveals particularly shallow deposits that future mission planners may want to study further.
While there are lots of places on Mars scientists would like to visit, few would make practical landing sites for astronauts. Most scientists have homed in on the northern and southern mid-latitudes, which have more plentiful sunlight and warmer temperatures than the poles. But there's a heavy preference for landing in the northern hemisphere, which is generally lower in elevation and provides more atmosphere to slow a landing spacecraft. A large portion of a region called Arcadia Planitia is the most tempting target in the northern hemisphere. The map shows lots of blue and purple in this region, representing water ice less than 30 centimetres below the surface; warm colours are over 60 centimetres deep. Sprawling black zones on the map represent areas where a landing spacecraft would sink into fine dust.

'TIGER STRIPES' OF ENCELADUS
University of California - Davis

Saturn's tiny, frozen moon Enceladus is a strange place. Just 300 miles across, the moon is thought to have an outer shell of ice covering a global ocean 20 miles deep, encasing a rocky core. Slashed across Enceladus' south pole are four straight, parallel fissures or "tiger stripes" from which water erupts. The fissures aren't quite like anything else in the Solar
System. Saturn's gravity exerts tidal forces on Enceladus, which cause heating and cooling of the tiny world. Those forces are strongest at the poles. As liquid water solidifies into ice under the outer ice shell, it expands in volume, putting pressure on the ice until it cracks. Enceladus'
surface temperature is about minus 200 degrees Celsius, so if a crack formed in the ice, you would expect it to freeze shut pretty quickly. Yet the south polar fissures remain open, and in fact reach all the way to the liquid ocean below. That's because liquid water within the fissure is sloshed around by tidal forces produced by Saturn's gravity, releasing energy as heat. That stops the crack from freezing shut. The release of pressure from the fissures stops new cracks from forming elsewhere on the moon, such as at the north pole. But at the same time, water vented from the crack falls back as ice, building up the edges of the fissure and weighing it down a bit. That causes the ice sheet to flex, the researchers calculate, just enough to set off a parallel crack about 20 miles away.

OSIRIS-REx EXPLAINS BENNU MYSTERY PARTICLES
NASA

Shortly after NASA's OSIRIS-REx spacecraft arrived at asteroid Bennu, an unexpected discovery by the mission's science team revealed that the asteroid could be active, or consistently discharging particles into space.  The ongoing examination of Bennu -- and its sample that will eventually be returned to Earth -- could potentially shed light on why this intriguing phenomenon is occurring. The OSIRIS-REx team first observed a particle-
ejection event in images captured by the spacecraft's navigation cameras taken on Jan. 6, just a week after the spacecraft entered its first orbit around Bennu. At first glance, the particles appeared to be stars behind the asteroid, but on closer examination, the team realized that the asteroid was ejecting material from its surface. After concluding that these particles did not compromise the spacecraft's safety, the mission began dedicated observations in order fully to document the activity. The team observed the three largest particle-ejection events on Jan. 6 and 19 and Feb. 11, and concluded that the events originated from different locations on Bennu's surface. The first event originated in the southern hemisphere, and the second and third events occurred near the equator. All three events took place in the late afternoon on Bennu.
The team found that, after ejection from the asteroid's surface, the particles either briefly orbited Bennu and fell back to its surface or escaped from Bennu into space. The observed particles travelled up to 3 metres per second, and measured smaller than 10 centimetres in size.  Approximately 200 particles were observed during the largest event, which took place on Jan. 6. The team investigated a wide variety of possible mechanisms that may have caused the ejection events and narrowed the list to three candidates: meteoroid impacts, thermal stress fracturing and released water vapour. Meteoroid impacts are common in the deep space neighbourhood of Bennu, and it is possible that these small fragments of space rock could be hitting Bennu where OSIRIS-REx is not observing it, shaking loose particles with the momentum of their impact. The team also determined that thermal fracturing is another reasonable explanation. Bennu's surface temperatures vary drastically over its 4.3-hour rotation period. Although it is extremely cold during the night hours, the asteroid's surface warms significantly in the mid-afternoon, which is when the three major events occurred. As a result of this temperature change, rocks may begin to crack and break down, and eventually particles could be ejected from the surface.  This cycle is known as thermal stress fracturing.
Water release may also explain the asteroid's activity. When Bennu's water-locked clays are heated, the water could begin to release and create pressure. It is possible that as pressure builds in cracks and pores in boulders where absorbed water is released, the surface could become agitated, causing particles to erupt. But nature does not always allow for simple explanations. It could be that more than one of these possible mechanisms at play, for example, thermal fracturing could be chopping the surface material into small pieces, making it far easier for meteoroid impacts to launch pebbles into space. If thermal fracturing, meteoroid
impacts or both are in fact the causes of these ejection events, then this phenomenon is probably happening on all small asteroids, as they all experience these mechanisms. However, if water release is the cause of these ejection events, then that phenomenon would be specific to asteroids that contain water-bearing minerals, like Bennu.
Bennu's activity presents larger opportunities once a sample is collected and returned to Earth for study. Many of the ejected particles are small enough to be collected by the spacecraft's sampling mechanism, meaning that the returned sample may possibly contain some material that was ejected and returned to Bennu's surface. Determining that a particular particle had been ejected and returned to Bennu might be a scientific feat similar to finding a needle in a haystack. The material returned to Earth from Bennu, however, will almost certainly increase our understanding of asteroids and the ways they are both different and similar, even as the particle-ejection phenomenon continues to be a mystery whose clues we'll also return home with in the form of data and further material for study. Sample collection is scheduled for summer 2020, and the sample will be delivered to Earth in September 2023.

FIRST WHITE DWARF PLANET FOUND
ESO

Researchers using the Very Large Telescope have, for the first time, found evidence of a giant planet associated with a white-dwarf star. The planet orbits the hot white dwarf, the remnant of a Sun-like star, at close range, causing its atmosphere to be stripped away and form a disc of gas around the star. This unique system hints at what our own Solar System might look like in the distant future. The team had inspected around 7000 white dwarfs
observed by the Sloan Digital Sky Survey and found one to be unlike any other. By analysing subtle variations in the light from the star, they found traces of chemical elements in amounts that scientists had never before observed at a white dwarf. To get a better idea of the properties of this unusual star, named WDJ0914+1914, the team analysed it with the X-shooter instrument in the Chilean Atacama Desert. These follow-up observations confirmed the presence of hydrogen, oxygen and sulphur associated with the white dwarf. By studying the fine details in the spectra taken by ESO's X-shooter, the team discovered that these elements
were in a disc of gas swirling into the white dwarf, and not coming from the star itself. The detected amounts of hydrogen, oxygen and sulphur are similar to those found in the deep atmospheric layers of icy, giant planets like Neptune and Uranus. If such a planet were orbiting close to a hot white dwarf, the extreme ultraviolet radiation from the star would strip away its outer layers and some of the stripped gas would swirl into a disc, itself accreting onto the white dwarf. That is what scientists think they are seeing around WDJ0914+1914: the first evaporating planet orbiting a white dwarf.
Combining observational data with theoretical models, the team of astronomers from the UK, Chile and Germany were able to paint a clearer image of that unique system. The white dwarf is small and, at 28 000 degrees Celsius (five times the Sun's temperature), extremely hot. By contrast, the planet is icy and large -- at least twice as large as the star. Since it orbits the
hot white dwarf at close range, making its way around it in just 10 days, the high-energy photons from the star are gradually blowing away the planet's atmosphere. Most of the gas escapes, but some is pulled into a disc swirling into the star at a rate of 3000 tonnes per second. It is that disc that makes the otherwise hidden Neptune-like planet visible. Stars like our Sun burn hydrogen in their cores for most of their lives. Once they run out of that fuel, they puff up into red giants, becoming hundreds of times larger and engulfing nearby planets. In the case of the Solar System, this will include Mercury, Venus, and even Earth, which will all be consumed by the red-giant Sun in about 5 billion years. Eventually, Sun-like stars lose their outer layers, leaving behind only a burnt-out core, a white dwarf.  Such stellar remnants can still host planets, and many such star systems are thought to exist in our galaxy. However, until now, scientists had never found evidence of a surviving giant planet around a white dwarf. The
detection of an exoplanet in orbit around WDJ09 14+1914, located about 1500 light years away in the constellation Cancer, may be the first of many orbiting such stars. According to the researchers, the exoplanet now found with the help of ESO's X-shooter orbits the white dwarf at a distance of only 10 million kilometres, or 15 times the solar radius, which would have been deep inside the red giant. The unusual position of the planet implies that at some point after the host star became a white dwarf, the planet moved closer to it. The astronomers believe that the new orbit could be the result of gravitational interactions with other planets in the system,
meaning that more than one planet may have survived its host star's violent transition.

ANCIENT STARBURST FOUND IN MILKY WAY
ESO

Astronomers using the Very Large Telescope (VLT) have observed the central part of the Milky Way and uncovered new details about the history of star birth in our galaxy. Thanks to the new observations, astronomers have found evidence for a dramatic event in the life of the Milky Way: a burst of star formation so intense that it resulted in over a hundred thousand supernova explosions. In the study, the team found that about 80% of the stars in the Milky Way central region formed in the earliest years of our galaxy, between eight and 13.5 billion years ago. This initial period of star formation was followed by about six billion years during which very few stars were born. This was brought to an end by an intense burst of star formation around one billion years ago when, over a period of less than 100 million years, stars with a combined mass possibly as high as a few tens of million Suns formed in this central region. The conditions in the studied region during this burst of activity must have resembled those in "starburst" galaxies, which form stars at rates of more than 100 solar masses per year.  At present, the whole Milky Way is forming stars at a rate of about one or
two solar masses per year. This burst of activity, which must have resulted in the explosion of more than a hundred thousand supernovae, was probably one of the most energetic events in the whole history of the Milky Way.  During a starburst, many massive stars are created; since they have shorter lifespans than lower-mass stars, they reach the end of their lives much
faster, dying in violent supernova explosions.

Bulletin compiled by Clive Down
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 £22 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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Family tree chart - 10 Generation Double Chart (coloured boxes 120 g paper)

Capture.JPG

Available form Amazon £7.95 including p&p. CLICK HERE
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Screenshot_20191221-184630.png
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.............. The Pembrokeshire U3A Astronomy Group are visiting the Observatory https://spaceguardcentre.com/ at Knighton during the 1st week in March 2020, but walkers can drop off anywhere along the line a take stroll through beautiful a wild Mid-Wales.  We are driving to Llaneilo and catching the train (free if you have the new Wales Travel Pass), but you can set off from Haverfordwest and connect with the Heart of Wales line at Lanelli or Swansea.

Check out this temping article in the Countryfile Magazine https://www.countryfile.com/go-outdoors/walks/walk-heart-of-wales-line-trail-ccarmarthenshire/

16
Health and Well-being! / GROWING OLD IN THE 21ST CENTURY!
December 20, 2019, 08:50:19 am
GROWING OLD IN THE 21ST CENTURY!
Rowena (From the kitchen) "Geoff, Alexa has just reminded you - Have you take your pill?"
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General Chatty Stuff / The Election!
December 08, 2019, 01:05:56 pm
............It has just struck me. After the election on Thursday we wake up on FRIDAY THE 13TH!
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Members of the public can visit the Dyfed Shire Horse Farm for free today (Sunday) to help celebrate some very good news.  Ed the farm's five-year-old shire horse has been chosen as the newest member of the Queen's Household Cavalry.  The farm bought Ed as a yearling in 2016. He has now been chosen to follow the farm's other horse Celt Mercury Drumhorse into Royal service.
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 504 2019 December 8

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/
 
NEXT SOLAR CYCLE WILL BE LOWEST IN 200 YEARS
NASA

The forecast for the next solar cycle (25) suggests that it will be the weakest of the last 200 years. The maximum of this next cycle -- measured in terms of sunspot number, a standard measure of solar activity level -- could be 30 to 50% lower than the most recent one. The agency's results show that the next cycle will start in 2020 and reach its maximum in 2025.
The new research combined observations from two NASA space missions -- the Solar and Heliospheric Observatory and the Solar Dynamics Observatory -- with data collected since 1976 from the ground-based National Solar Observatory. One challenge for researchers working to predict the Sun's activities is that scientists don't yet completely understand the inner workings of our star. Plus, some factors that play out deep inside the Sun cannot be measured directly. They have to be estimated from measurements of related phenomena on the solar surface, like sunspots. The method differs from other prediction tools in terms of the raw material for its forecast.
Previously, researchers used the number of sunspots to represent indirectly the activity of the solar magnetic field. The new approach takes advantage of direct observations of magnetic fields emerging on the surface of the Sun -- data which have only existed for the last four solar cycles. Mathematically combining the data from the three sources of Sun observations with the estimates of its interior activity generated a forecast designed to be more reliable than from any of those sources alone. In 2008 the researchers used this method to make their prediction, which was then put to the test as the current solar cycle unfolded over the last decade. It has performed well, with the forecast strength and timing of the solar maximum aligning closely with reality.
NASA attempts to paint the upcoming solar shutdown as a window of opportunity for space missions. The improving ability to make such predictions about space weather are good news for mission planners who can schedule human exploration missions during periods of lower radiation. NASA is effectively forecasting a return to the Dalton Minimum (1790-1830) but gives no mention of the brutal cold, crop loss, famine, war and powerful volcanic eruptions associated with it. Like the deeper Maunder and Sporer Minima preceding it, the Dalton brought on a period of lower-than-average global temperatures. The Oberlach Station in Germany, for example, experienced a 2C decline over 20 years, which devastated the country's food production.  The Year Without a Summer also occurred during the Dalton Minimum, in 1816.  It was caused by a combination of already low temperatures plus the after-
effects of the second-largest volcanic eruption in 2000 years: Mount Tambora's, on 1815 April 10. And the story was the same across the world: the potato crop in Ireland rotted in the ground resulting in widespread starvation. In England, France and Germany wheat crops failed, leading to bread shortages and food riots and looting. Northern China was also hard
hit, with thousands of people starving to death, while in southern Asia, torrential rains triggered a cholera epidemic that killed many more. The year 1816 went on to earn another, rather more morbid nickname, "Eighteen Hundred and Froze to Death". Solar Cycle 25 will likely be a mere stop-off on our descent into the next Grand Solar Minimum -- a period of even further reduced temperatures and crop yields (research Maunder Minimum, 1645-1715).  And there are other researchers still insisting there won't be a solar cycle 25 at all.

GLOBAL STORMS ON MARS
NASA

Dust storms are common on Mars. But every decade or so, something unpredictable happens: a series of runaway storms breaks out, covering the entire planet in a dusty haze. Last year, a fleet of NASA spacecraft got a detailed look at the life cycle of the 2018 global dust storm that ended the Opportunity rover's mission. And while scientists are still puzzling over the data, two papers recently shed new light on a phenomenon observed within the storm: dust towers, or concentrated clouds of dust that warm in sunlight and rise high into the air. Scientists think that dust-trapped water vapour may be riding them like a lift to space, where solar radiation breaks apart  their molecules. That might help explain how Mars' water disappeared over billions of years. Dust towers are massive, churning clouds that are denser
and climb much higher than the normal background dust in the thin Martian atmosphere. While they also occur under normal conditions, the towers appear to form in greater numbers during global storms.
A tower starts at the planet's surface as an area of rapidly lifted dust about 60 km wide. By the time a tower reaches a height of 80 kilometres, as seen during the 2018 global dust storm, it may be as wide as 220 km.  As the tower decays, it can form a layer of dust 56 kilometres above the surface that can be wider than the continental United States. The recent findings on dust towers come courtesy of NASA's Mars Reconnaissance Orbiter (MRO), which is led by the agency's Jet Propulsion Laboratory in Pasadena, California. Though global dust storms cloak the planet's surface, MRO can use its heat-sensing Mars Climate Sounder instrument to see through the haze. The instrument is designed specifically for measuring dust levels.  Its data, coupled with images from a camera aboard the orbiter called the Mars Context Imager (MARCI), enabled scientists to detect numerous swelling dust towers.

FIRST GLOBAL MAP OF TITAN COMPLETED
NASA

The first map showing the global 'geology' of Saturn's largest moon, Titan, has been completed and fully reveals a dynamic world of dunes, lakes, plains, craters and other terrains. Titan is the only planetary body in our solar system other than Earth known to have stable liquid on its surface.  But instead of water raining down from clouds and filling lakes and seas as on Earth, on Titan what rains down is methane and ethane -- hydrocarbons that we think of as gases but are liquids in Titan's frigid climate.  Despite the different materials, temperatures and gravity fields between Earth and Titan, many surface features are similar between the two worlds
and can be interpreted as being products of the same geological processes.  The map shows that the different geological terrains have a clear distribution with latitude, globally, and that some terrains cover far more area than others. Scientists used data from NASA's Cassini mission, which operated between 2004 and 2017 and did more than 120 flybys of the Mercury-size moon. Specifically, they used data from Cassini's radar imager to penetrate Titan's opaque atmosphere of nitrogen and methane. In addition, the team used data from Cassini's visible and infrared instruments, which were able to capture some of Titan's larger geological features through the methane haze. The Cassini mission revealed that Titan is a geologically active world, where hydrocarbons like methane and ethane take the role that
water has on Earth. The hydrocarbons rain down on the surface, flow in streams and rivers, accumulate in lakes and seas, and evaporate into the atmosphere. It's quite an astounding world!
 
CLOSER TO SIGNAL FROM COSMIC DAWN
Brown University

Around 12 billion years ago, the Universe emerged from a great cosmic dark age as the first stars and galaxies lit up. With a new analysis of data collected by the Murchison Widefield Array (MWA) radio telescope, scientists are now closer than ever to detecting the ultra-faint signature of this turning point in cosmic history. The researchers configured the MWA
specifically to look for the signal of neutral hydrogen, the gas that dominated the Universe during the cosmic dark age. The analysis sets a new limit -- the lowest limit yet -- for the strength of the neutral hydrogen signal. Despite its importance in cosmic history, little is known about the period when the first stars formed, which is known as the Epoch of Reionization (EoR). The first atoms that formed after the Big Bang were positively charged hydrogen ions -- atoms whose electrons were stripped away by the energy of the infant Universe. As the Universe cooled and expanded, hydrogen atoms reunited with their electrons to form neutral hydrogen. And that's just about all there was in the Universe until about 12 billion years
ago, when atoms started clumping together to form stars and galaxies. Light from those objects re-ionized the neutral hydrogen, causing it to largely disappear from interstellar space. The goal of projects like the one happening at MWA is to locate the signal of neutral hydrogen from the dark ages and measure how it changed as the EoR unfolded. Doing so could reveal
new and critical information about the first stars -- the building blocks of the Universe we see today. But catching any glimpse of that 12-billion-year-old signal is a difficult task that requires instruments with very high sensitivity.
When it began operating in 2013, the MWA was an array of 2,048 radio antennae arranged across the remote countryside of Western Australia. The antennae are bundled together into 128 'tiles', whose signals are combined by a supercomputer called the Correlator. In 2016, the number of tiles was doubled to 256, and their configuration across the landscape was altered to improve their sensitivity to the neutral hydrogen signal. The new paper is the first analysis of data from the expanded array. Neutral hydrogen emits radiation at a wavelength of 21 centimetres. As the Universe has expanded over the past 12 billion years, the signal from the EoR is now stretched to about 2 metres, and that's what MWA astronomers are looking for. The  problem is there are myriad other sources that emit at the same wavelength -- human-made sources like digital television as well as natural sources from within the Milky Way and from millions of other galaxies. The other sources are many orders of magnitude stronger than the signal we're trying to detect. Even an FM radio signal that's reflected off an aeroplane that
happens to be passing above the telescope is enough to contaminate the data. To home in on the signal, the researchers use a myriad of processing techniques to weed out those contaminants. At the same time, they account for the unique frequency responses of the telescope itself. Those data-analysis techniques, combined with the expanded capacity of the telescope itself, resulted in a new upper bound of the EoR signal strength. It's the second consecutive best-limit-to-date analysis to be released by MWA and raises hope that the experiment will one day detect the elusive EoR signal.

HOW BLACK HOLES AND NEUTRON STARS SHINE BRIGHT
Columbia University

For decades, scientists have speculated about the origin of the electromagnetic radiation emitted from celestial regions that host black holes and neutron stars -- the most mysterious objects in the Universe. Astrophysicists believe that that high-energy radiation -- which makes neutron stars and black holes shine bright -- is generated by electrons that move at nearly the speed of light, but the process that accelerates these particles has remained a mystery. Now, researchers have employed massive super-computer simulations to calculate the mechanisms that accelerate those particles. They concluded that their energization is a result of the interaction between chaotic motion and reconnection of super-strong magnetic fields. Turbulence and magnetic reconnection -- a process in which magnetic field lines tear and rapidly reconnect -- conspire together to accelerate particles, boosting them to velocities that approach the speed of light.  The region that hosts black holes and neutron stars is permeated by an extremely hot gas of charged particles, and the magnetic field lines dragged by the chaotic motions of the gas drive vigorous magnetic reconnection. It is thanks to the electric field induced by reconnection and turbulence that particles are accelerated to the most extreme energies, much higher than in the most powerful accelerators on Earth, such as the Large Hadron Collider at CERN. When studying turbulent gas, scientists cannot predict chaotic motion precisely. Dealing with the mathematics of turbulence is difficult, and it
constitutes one of the seven "Millennium Prize" mathematical problems. To tackle this challenge from an astrophysical point of view, researchers designed extensive super-computer simulations -- among the world's largest ever done in this research area -- to solve the equations that describe the turbulence in a gas of charged particles.
They used the most precise technique -- the particle-in-cell method -- for calculating the trajectories of hundreds of billions of charged particles that self-consistently dictate the electromagnetic fields. And it is this electromagnetic field that tells them how to move. The crucial point of the study was to identify the role that magnetic reconnection plays within the
turbulent environment. The simulations showed that reconnection is the key mechanism that selects the particles that will be subsequently accelerated by the turbulent magnetic fields up to the highest energies. The simulations also revealed that particles gained most of their energy by bouncing  randomly at an extremely high speed off the turbulence fluctuations. When the magnetic field is strong, this acceleration mechanism is very rapid.  But the strong fields also force the particles to travel in curved paths, and by doing so, they emit electromagnetic radiation. That is indeed the radiation emitted around black holes and neutron stars that make them shine, a phenomenon we can observe on Earth. The ultimate goal is to get to know what is really going on in the extreme environment surrounding black holes and neutron stars, which could shed additional light on fundamental physics and improve our understanding of how our Universe works. The researchers plan to connect their work even more firmly with observations, by comparing their predictions with the electromagnetic spectrum emitted from the Crab Nebula, the most intensely studied bright remnant of a supernova (a star that violently exploded in the year 1054). This will be a stringent test for their theoretical explanation.