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Science & Nature / Mid August Astronomy Bulletin
« Last post by Clive on August 12, 2022, 09:31 »

Earth Sky

On July 29, the Earth broke its record for the shortest day as it completed a full spin in 1.59 milliseconds less than its standard 24-hour rotation. The planet recently has been increasing its speed. Back in 2020, the Earth saw its shortest month that has ever been recorded since the 1960s. On July 19 of that year, the shortest of all time was measured. It was 1.47 milliseconds shorter than a typical 24-hour day. The next year, the planet continued to spin at a generally increased rate, but it did not break any records. However, according to some scientists a 50-year phase of shorter days may be starting right now. The cause of the differing speed of Earth's spin is still unknown. But scientists speculate that this could be because of processes in the inner or outer layers of the core, oceans, tides or even changes in climate. Some researchers also believe that this could be related to the movement of Earth's geographic poles across its surface, known as the "Chandler wobble". In simpler words, this is similar to the quiver one sees when a spinning top starts gaining momentum or slows down.

If the Earth continues to spin at an increasing rate it could lead to the introduction of the negative leap seconds, in a bid to keep the rate that the Earth orbits the Sun consistent with the measurement from atomic clocks. However, the negative leap second would have potentially confusing consequences for smartphones, computers and communications systems. Citing a Meta blog, the outlet reported that the leap second "mainly benefits scientists and astronomers" but that it is a "risky practice that does more harm than good". This is because the clock progresses from 23:59:59 to 23:59:60 before resetting to 00:00:00. A time jump like this can, therefore, crash programmes and corrupt data due to the timestamps on the data storage. Should a negative leap second occur, the clock will change from 23:59:58 to 00:00:00, and this could have a "devastating effect" on the software relying on timers and schedulers. According to IE, to solve this, international timekeepers may need to add a negative leap second - a "drop second". Notably, Coordinated Universal Time (UTC), the primary time standard by which the world regulates clocks and time, has already been updated with a leap second 27 times.


National Institutes of Natural Sciences

A super-Earth planet has been found near the habitable zone of a red dwarf star only 37 light-years from the Earth. This is the first discovery by a new instrument on the Subaru Telescope and offers a chance to investigate the possibility of life on planets around nearby stars. With such a successful first result, we can expect that the Subaru Telescope will discover more, potentially even better, candidates for habitable planets around red dwarfs. Red dwarfs, stars smaller than the Sun, account for three-quarters of the stars in the Milky Way Galaxy, and are abundant in the neighbourhood around the Sun. As such, they are important targets in the search for nearby extra-solar planets and extraterrestrial life. But red dwarfs are cool and don't emit much visible light compared to other types of stars, making it difficult to study them. In the infrared wavelengths red dwarfs are brighter. So the Astrobiology Center in Japan developed an infrared observational instrument mounted on the Subaru Telescope to search for signs of planets around red dwarf stars. The instrument is called IRD for Infrared Doppler, the observational method used in this search. The first fruits of this search are signs of a super-Earth four times the mass of the Earth circling the star Ross 508, located 37 light-years away in the constellation Serpens. This planet, Ross 508 b, has a year of only 11 Earth-days, and lies at the inner edge of the habitable zone around its host star. Interestingly, there are indications that the orbit is elliptical, which would mean that for part of the orbit the planet would be in the habitable zone, the region where conditions would be right for liquid water to exist on the surface of the planet. Whether or not there is actually water or life are questions of further study.


University of California - Los Angeles

A team of planetary scientists has discovered shady locations within pits on the Moon that always hover around a comfortable 15 degrees centigrade. The pits, and caves to which they may lead, would make safer, more thermally stable base camps for lunar exploration and long-term habitation than the rest of the Moon's surface, which heats up to 127 degrees during the day and drops to 138 degrees below zero at night. Pits were first discovered on the Moon in 2009, and since then, scientists have wondered if they led to caves that could be explored or used as shelters. About 16 of the more than 200 pits are probably collapsed lava tubes. Two of the most prominent pits have visible overhangs that clearly lead to some sort of cave or void, and there is strong evidence that another's overhang may also lead to a large cave. Lava tubes, also found on Earth, form when molten lava flows beneath a field of cooled lava or a crust forms over a river of lava, leaving a long, hollow tunnel. If the ceiling of a solidified lava tube collapses, it opens a pit that can lead into the rest of the cave-like tube. Scientists processed images from the Diviner Lunar Radiometer Experiment -- a thermal camera and one of six instruments on NASA's robotic Lunar Reconnaissance Orbiter -- to find out if the temperature within the pits diverged from those on the surface. Focusing on a roughly cylindrical 100-metre-deep in Mare Tranquillitatis, the team used computer modelling to analyse the thermal properties of the rock and lunar dust and to chart the pit's temperatures over a period of time. The results revealed that temperatures within the permanently shadowed reaches of the pit fluctuate only slightly throughout the lunar day, remaining at around 15 degrees. If a cave extends from the bottom of the pit, as images taken by the Lunar Reconnaissance Orbiter Camera suggest, it too would have this relatively comfortable temperature.

A day on the Moon lasts nearly 15 Earth days, during which the surface is constantly bombarded by sunlight and is frequently hot enough to boil water. Unimaginably cold nights also last about 15 Earth days. Inventing heating and cooling equipment that can operate under these conditions and producing enough energy to power it nonstop could prove an insurmountable barrier to lunar exploration or habitation. Solar power -- NASA's most common form of power generation -- doesn't work at night, after all. (NASA currently has no plans to establish an exploration base camp or habitations on the Moon.) Building bases in the shadowed parts of these pits allows scientists to focus on other challenges, like growing food, providing oxygen for astronauts, gathering resources for experiments and expanding the base. The pits or caves would also offer some protection from cosmic rays, solar radiation and micrometeorites. Diviner has been mapping the Moon continuously since 2009, producing NASA's second largest planetary dataset and providing the most detailed and comprehensive thermal measurements of any object in our solar system, including Earth. The team's current work on lunar pits has improved data from the Diviner experiment. Data from the early stages of this lunar pit thermal modelling project were used to help develop the thermal management system of the rover for NASA's proposed Moon Diver mission.


University of California - Berkeley

Millisecond pulsars spin far more rapidly than expected for a collapsed star. The best chance to study these neutron stars is to find a black widow system where the pulsar has evaporated and eaten much of its companion star. The Keck I telescope was just able to capture spectra of one such companion, allowing astronomers to weigh its pulsar. It's the heaviest found to date, and perhaps near the upper limit for a neutron star. A dense, collapsed star spinning 707 times per second -- making it one of the fastest spinning neutron stars in the Milky Way galaxy -- has shredded and consumed nearly the entire mass of its stellar companion and, in the process, grown into the heaviest neutron star observed to date. Weighing this record-setting neutron star, which is 2.35 times the mass of the Sun, helps astronomers understand the weird quantum state of matter inside these dense objects, which -- if they get much heavier than that -- collapse entirely and disappear as a black hole. A neutron star is like one giant nucleus, but when you have one-and-a-half solar masses of this stuff, masses of nuclei all clinging together, it's not at all clear how they will behave. Neutron stars are so dense -- 1 cubic inch weighs over 10 billion tons -- that their cores are the densest matter in the Universe short of black holes, which because they are hidden behind their event horizon are impossible to study. The neutron star, a pulsar designated PSR J0952-0607, is thus the densest object within sight of Earth. The measurement of the neutron star's mass was possible thanks to the extreme sensitivity of the 10-meter Keck I telescope on Maunakea in Hawai'i, which was just able to record a spectrum of visible light from the hotly glowing companion star, now reduced to the size of a large gaseous planet. The stars are about 3,000 light years from Earth in the direction of the constellation Sextans.

If 2.35 solar masses is close to the upper limit of neutron stars, the researchers say, then the interior is likely to be a soup of neutrons as well as up and down quarks -- the constituents of normal protons and neutrons -- but not exotic matter, such as "strange" quarks or kaons, which are particles that contain a strange quark. Astronomers generally agree that when a star with a core larger than about 1.4 solar masses collapses at the end of its life, it forms a dense, compact object with an interior under such high pressure that all atoms are smashed together to form a sea of neutrons and their subnuclear constituents, quarks. These neutron stars are born spinning, and though too dim to be seen in visible light, reveal themselves as pulsars, emitting beams of light -- radio waves, X-rays or even gamma rays -- that flash Earth as they spin, much like the rotating beam of a lighthouse. "Ordinary" pulsars spin and flash about once per second, on average, a speed that can easily be explained given the normal rotation of a star before it collapses. But some pulsars repeat hundreds or up to 1,000 times per second, which is hard to explain unless matter has fallen onto the neutron star and spun it up. But for some millisecond pulsars, no companion is visible. One possible explanation for isolated millisecond pulsars is that each did once have a companion, but it stripped it down to nothing. The pulsar PSR J0952-0607 and its faint companion star support this origin story for millisecond pulsars. Finding black widow pulsars in which the companion is small, but not too small to detect, is one of few ways to weigh neutron stars. In the case of this binary system, the companion star -- now only 20 times the mass of Jupiter -- is distorted by the mass of the neutron star and tidally locked, similar to the way our Moon is locked in orbit so that we see only one side. The neutron star-facing side is heated to temperatures of about 6,200 Kelvin, a bit hotter than our Sun, and just bright enough to see with a large telescope.


National Radio Astronomy Observatory

Scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) have made the first-ever detection of gas in a circumplanetary disk. What's more, the detection also suggests the presence of a very young exoplanet. Circumplanetary disks are an amassing of gas, dust, and debris around young planets. These disks give rise to moons and other small, rocky objects, and control the growth of young, giant planets. Studying these disks in their earliest stages may help shed light on the formation of our own Solar System, including that of Jupiter's Galilean moons, which scientists believe formed in a circumplanetary disk of Jupiter around 4.5 billion years ago. While studying AS 209 -- a young star located roughly 395 light-years from Earth in the constellation Ophiuchus -- scientists observed a blob of emitted light in the middle of an otherwise empty gap in the gas surrounding the star. That led to the detection of the circumplanetary disk surrounding a potential Jupiter-mass planet. Scientists are watching the system closely, both because of the planet's distance from its star and the star's age. The exoplanet is located more than 200 astronomical units, or 18.59 billion miles, away from the host star, challenging currently accepted theories of planet formation. And if the host star's estimated age of just 1.6 million years holds true, this exoplanet could be one of the youngest ever detected. Further study is needed, and scientists hope that upcoming observations with the James Webb Space Telescope will confirm the planet's presence. Scientists have long suspected the presence of circumplanetary disks around exoplanets, but until recently were unable to prove it. In 2019, ALMA scientists made the first-ever detection of a circumplanetary, moon-forming disk while observing the young exoplanet PDS 70c, and confirmed the find in 2021. The new observations of gas in a circumplanetary disk at AS 209 may shed further light on the development of planetary atmospheres and the processes by which moons are formed.


University of Bonn

Dwarf galaxies are small, faint galaxies that can usually be found in galaxy clusters or near larger galaxies. Because of this, they might be affected by the gravitational effects of their larger companions. Tides arise when gravity from one body pulls differently on different parts of another body. These are similar to tides on Earth, which arise because the Moon pulls more strongly on the side of Earth which faces the Moon. The Fornax Cluster has a rich population of dwarf galaxies. Recent observations show that some of these dwarfs appear distorted, as if they have been perturbed by the cluster environment. Scientists analysed the expected level of disturbance of the dwarfs, which depends on their internal properties and their distance to the gravitationally powerful cluster centre. Galaxies with large sizes but low stellar masses and galaxies close to the cluster centre are more easily disturbed or destroyed. They compared the results with their observed level of disturbance evident from photographs taken by the VLT Survey Telescope of the European Southern Observatory. The comparison showed that, if one wants to explain the observations in the standard model, the Fornax dwarfs should already be destroyed by gravity from the cluster centre even when the tides it raises on a dwarf are sixty-four times weaker than the dwarf's own self-gravity. Not only is this counter-intuitive, it also contradicts previous studies, which found that the external force needed to disturb a dwarf galaxy is about the same as the dwarf's selfgravity.

From this, the team concluded that, in the standard model, it is not possible to explain the observed morphologies of the Fornax dwarfs in a self-consistent way. They repeated the analysis using Milgromian dynamics (MOND). Instead of assuming dark matter halos surrounding galaxies, the MOND theory proposes a correction to Newtonian dynamics by which gravity experiences a boost in the regime of low accelerations. It is not certain that the dwarf galaxies would be able to survive the extreme environment of a galaxy cluster in MOND, due to the absence of protective dark matter halos in this model, but the results show a remarkable agreement between observations and the MOND expectations for the level of disturbance of the Fornax dwarfs. This is not the first time that a study testing the effect of dark matter on the dynamics and evolution of galaxies concluded that observations are better explained when they are not surrounded by dark matter. The number of publications showing incompatibilities between observations and the dark matter paradigm just keeps increasing every year.


Nagoya University

Japanese scientists have investigated the nature of dark matter surrounding galaxies seen as they were 12 billion years ago, billions of years further back in time than ever before. Seeing something that happened such a long time ago is difficult. Because of the finite speed of light, we see distant galaxies not as they are today, but as they were billions of years ago. But even more challenging is observing dark matter, which does not emit light. Consider a distant source galaxy, even further away than the galaxy whose dark matter one wants to investigate. The gravitational pull of the foreground galaxy, including its dark matter, distorts the surrounding space and time, as predicted by Einstein's theory of general relativity. As the light from the source galaxy travels through this distortion, it bends, changing the apparent shape of the galaxy. The greater the amount of dark matter, the greater the distortion. Thus, scientists can measure the amount of dark matter around the foreground galaxy (the "lens" galaxy) from the distortion. However, beyond a certain point scientists encounter a problem. The galaxies in the deepest reaches of the Universe are incredibly faint. As a result, the further away from Earth we look, the less effective this technique becomes. The lensing distortion is subtle and difficult to detect in most cases, so many background galaxies are necessary to detect the signal. Most previous studies have remained stuck at the same limits. Unable to detect enough distant source galaxies to measure the distortion, they could only analyze dark matter from no more than 8-10 billion years ago. These limitations left open the question of the distribution of dark matter between this time and 13.7 billion years ago, around the beginning of our Universe.

To overcome these challenges and observe dark matter from the furthest reaches of the Universe, a research team used a different source of background light, the microwaves released from the Big Bang itself. First, using data from the observations of the Subaru Hyper Suprime-Cam Survey (HSC), the team identified 1.5 million lens galaxies using visible light, selected to be seen 12 billion years ago. Next, to overcome the lack of galaxy light even further away, they employed microwaves from the cosmic microwave background (CMB), the radiation residue from the Big Bang. Using microwaves observed by the European Space Agency's Planck satellite, the team measured how the dark matter around the lens galaxies distorted the microwaves. After a preliminary analysis, the researchers soon realized that they had a large enough sample to detect the distribution of dark matter. Combining the large distant galaxy sample and the lensing distortions in CMB, they detected dark matter even further back in time, from 12 billion years ago. This is only 1.7 billion years after the beginning of the Universe, and thus these galaxies are seen soon after they first formed. One of the most exciting findings of the researchers was related to the clumpiness of dark matter. According to the standard theory of cosmology, the Lambda-CDM model, subtle fluctuations in the CMB form pools of densely packed matter by attracting surrounding matter through gravity. This creates inhomogeneous clumps that form stars and galaxies in these dense regions. The group's findings suggest that their clumpiness measurement was lower than predicted by the Lambda-CDM model.



After insinuating that it planned to leave the International Space Station partnership after 2024, Russia’s state space corporation Roscosmos has told NASA that it intends to remain in the program until at least 2028. Roscosmos plans to stay involved with the ISS until it gets a new Russian space station up and running, with 2028 as the target date. NASA and Roscosmos are the two biggest partners on the International Space Station, and both entities are tasked with operating the vehicle and maintaining a continuous human presence on the ISS while in orbit. However, growing tensions between the United States and Russia over the latter’s invasion of Ukraine have prompted concern about the future of the ISS partnership. NASA still plans to operate the vehicle until 2030, and it appears that Roscosmos will be on board for most of that time.



Despite signs of wear, the intrepid spacecraft is about to start an exciting new chapter of its mission as it climbs a Martian mountain.  Ten years ago, a jetpack lowered NASA’s Curiosity rover onto the Red Planet, beginning the SUV-size explorer’s pursuit of evidence that, billions of years ago, Mars had the conditions needed to support microscopic life.  Since then, Curiosity has driven nearly 18 miles and ascended 2,050 feet as it explores Gale Crater and the foothills of Mount Sharp within it. The rover has analysed 41 rock and soil samples, relying on a suite of science instruments to learn what they reveal about Earth’s rocky sibling. And it’s pushed a team of engineers to devise ways to minimize wear and tear and keep the rover rolling: In fact, Curiosity’s mission was recently extended for another three years, allowing it to continue among NASA’s fleet of important astrobiological missions. It’s been a busy decade. Curiosity has studied the Red Planet’s skies, capturing images of shining clouds and drifting moons. The rover’s radiation sensor lets scientists measure the amount of high-energy radiation future astronauts would be exposed to on the Martian surface, helping NASA figure out how to keep them safe. But most important, Curiosity has determined that liquid water as well as the chemical building blocks and nutrients needed for supporting life were present for at least tens of millions of years in Gale Crater. The crater once held a lake, the size of which waxed and waned over time. Each layer higher up on Mount Sharp serves as a record of a more recent era of Mars’ environment.  Now, out, leaving behind salty minerals called sulphates. Curiosity has made striking progress up the mountain. Back in 2015, the team captured a “postcard” image of distant buttes. A mere speck within that image is a Curiosity-size boulder nicknamed “Ilha Novo Destino” – and, nearly seven years later, the rover trundled by it last month on the way to the sulphate-bearing region. The team plans to spend the next few years exploring the sulphate-rich area. Within it, they have targets in mind like the Gediz Vallis channel, which may have formed during a flood late in Mount Sharp’s history, and large cemented fractures that show the effects of groundwater higher up the mountain.

DON MACHHOLZ 1952-2022


Don Machholz visually discovered 12 comets that bear his name. He was one of the inventors of the Messier marathon, which amateur astronomers around the world use to test their skill. It’s sad to announce the passing of Don Machholz on August 9, 2022, at his home – Stargazer Ranch, Arizona. Don became interested in astronomy at age 8. With this in mind, he received his first telescope on October 7, 1965, a 2-inch (5-cm) refractor. Later, he received a 6-inch (15-cm) Criterion Dynascope and found all the Messier Objects in one year (1969-70). Consequently, he decided to attempt a comet hunting program, which he began on January 1, 1975. He found his first comet on September 12, 1978, after 1,700 hours of searching. Subsequently, his second find took an additional 1,742 hours. Eventually, he spent 8,900 hours comet hunting, during which he discovered a total of 12 comets which bear his name. He was, in fact, the number one living visual comet discoverer.
The Laughter Zone / Re: CATHOLIC HORSES
« Last post by Clive on August 11, 2022, 19:01 »
Love it!   ;D
The Laughter Zone / CATHOLIC HORSES
« Last post by Den on August 11, 2022, 09:06 »
Before you read this please understand I have no denominational faith at all so any insult to any faith is purely accidental.


A punter was at the horse races playing the ponies and all but losing his shirt.

He noticed a Priest step out onto the track and blessed the forehead of one of the horses lining up for the 4th race.

Lo and behold, that horse - a very long shot - won the race.

Next race, as the horses lined up, the Priest stepped onto the track. Sure enough, he blessed one of the horses.

The punter made a beeline for a betting window and placed a small bet on the horse.  Again, even though it was another long shot, the horse won the race.

He collected his winnings, and anxiously waited to see which horse the Priest would bless next.

He bet big on it, and it won. As the races continued the Priest kept blessing long shots, and each one ended up winning.

The punter was elated. He made a quick dash to the ATM, withdrew all his savings, and awaited for the Priest's blessing that would tell him which horse to bet on ..

True to his pattern, the Priest stepped onto the track for the last race and blessed the forehead of an old nag that was the longest shot of the day.

This time the priest blessed the eyes, ears, and hooves of the old nag. The punter knew he had a winner and bet every cent he owned on the old nag.

He watched dumbfounded as the old nag came in last. In a state of shock, he went to the track area where the Priest was.

Confronting Him, he demanded, 'Father! What happened? All day long you blessed horses and they all won. Then in the last race, the horse you blessed lost by a mile. Now, thanks to you I've lost every cent of my savings!'.

The Priest nodded wisely and with sympathy.

'Son,' he said, 'that's the problem with you Protestants, you can't tell the difference between a simple blessing and last rites.'    o:)
The Laughter Zone / Re: hot weather
« Last post by Clive on August 11, 2022, 06:31 »
The Laughter Zone / Re: hot weather
« Last post by Simon on August 10, 2022, 22:48 »
The Laughter Zone / Re: hot weather
« Last post by Den on August 10, 2022, 21:53 »
I've just sold my homing pigeon on Ebay for the 22nd time.  ;)
Science & Nature / Late July Astronomy Bulletin
« Last post by Clive on July 31, 2022, 09:29 »

Johns Hopkins University Applied Physics Laboratory

Using data collected over two decades ago, scientists from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, have compiled the first complete map of hydrogen abundances on the Moon's surface. The map identifies two types of lunar materials containing enhanced hydrogen and corroborates previous ideas about lunar hydrogen and water, including findings that water likely played a role in the Moon's original magma-ocean formation and solidification. Researchers used orbital neutron data from the Lunar Prospector mission to build their map. The probe, which was deployed by NASA in 1998, orbited the Moon for a year and a half and sent back the first direct evidence of enhanced hydrogen at the lunar poles, before impacting the lunar surface. When a star explodes, it releases cosmic rays, or high-energy protons and neutrons that move through space at nearly the speed of light. When those cosmic rays come into contact with the surface of a planet, or a moon, they break apart atoms located on those bodies, sending protons and neutrons flying. Scientists are able to identify an element and determine where and how much of it exists by studying the motion of those protons and neutrons. The team calibrated the data to quantify the amount of hydrogen by the corresponding decrease of neutrons measured by the Neutron Spectrometer, one of five instruments mounted on Lunar Prospector to complete gravitational and compositional maps of the Moon.

The team's map confirms enhanced hydrogen in two types of lunar materials. The first, at the Aristarchus Plateau, is home to the Moon's largest pyroclastic deposit. These deposits are fragments of rock erupted from volcanoes, corroborating prior observations that hydrogen and/or water played a role in lunar magmatic events. The second is KREEP-type rocks. KREEP is an acronym for lunar lava rock that stands for potassium (K), rare earth elements (REE) and phosphorus (P). When the Moon originally formed, it's largely accepted that it was molten debris from a huge impact with Earth. As it cooled, minerals formed out of the melt, and KREEP is thought to be the last type of material to crystallize and harden. The new map not only completes the inventory of hydrogen on the Moon but could also lead to quantification of how much hydrogen and water was present in the Moon when it was born. In 2013, APL researchers also confirmed the presence of water ice at the poles on the planet Mercury using data from the neutron spectrometer on the APL-built MESSENGER spacecraft. These discoveries are important not only for understanding the solar system but also in planning future human exploration of the solar system.


Northern Arizona University

These days, not so much. But more than 4.5 billion years ago, it's possible the Red Planet had a crust comparable to Iceland today. This discovery, hidden in the oldest Martian fragments found on Earth, could provide information about our planet that was lost over billions of years of geological movement and could help explain why the Earth developed into a planet that sustains a broad diversity of life and Mars did not. These insights into Earth's past came out of a new study that details how they found the likely Martian origin of the 4.48-billion-year-old meteorite, informally named Black Beauty. Its origin is one of the oldest regions of Mars. The team searched for the location of origin of a Martian meteorite (officially named NWA -- Northwest Africa -- 7034 for where it was found on Earth). This meteorite, the chemistry of which indicates that Mars had volcanic activity to that found on Earth, recorded the first stage of Mars' evolution. Although it was ejected from the surface of Mars five to 10 million years ago after an asteroid impact, its source region and geological context has remained a mystery. This team studied chemical and physical properties of Black Beauty to pinpoint where it came from; they determined it was from Terra Cimmeria-Sirenum, one of the most ancient regions of Mars. It may have a surface similar to Earth's continents. Planetary bodies like Mars have impacts craters all over their surface, so finding the right one is challenging. In a previous study, The team developed a crater detection algorithm that uses high-resolution images of the surface of Mars to identify small impact craters, finding about 90 million as small as 50 metres in diameter. In this study, they were able to isolate the most plausible ejection site -- the Karratha crater that excavated ejecta of an older crater named Khujirt. The team's algorithm is adapted to detect impact craters constellating Mercury and the Moon, the other terrestrial bodies. This can be used to help unravel their geographical history and answer foundational questions regarding their formation and evolution. This work is a starting point to guide future investigations of the Solar System.


University of California - Riverside

Because it's bigger, Jupiter ought to have larger, more spectacular rings than Saturn has. But new research shows Jupiter's massive moons prevent that vision from lighting up the night sky. To understand the reason Jupiter currently looks the way it does, astronomers ran a dynamic computer simulation accounting for the orbits of Jupiter's four main moons, as well as the orbit of the planet itself, and information about the time it takes for rings to form. Saturn's rings are largely made of ice, some of which may have come from comets, which are also largely made of ice. If moons are massive enough, their gravity can toss the ice out of a planet's orbit, or change the orbit of the ice enough so that it collides with the moons. All four giant planets in our solar system -- Saturn, Neptune, Uranus and also Jupiter -- do in fact have rings. However, both Neptune and Jupiter's rings are so flimsy they're difficult to view with traditional stargazing instruments. Coincidentally, some of the recent images from the newly commissioned James Webb Space Telescope included pictures of Jupiter, in which the faint rings are visible. Uranus has rings that are aren't as large but are more substantial than Saturn's. Going forward, Kane intends to run simulations of the conditions on Uranus to see what the lifetime of that planet's rings might be. Some astronomers believe Uranus is tipped over on its side as the result of a collision the planet had with another celestial body. Its rings could be the remains of that impact. Beyond their beauty, rings help astronomers understand the history of a planet, because they offer evidence of collisions with moons or comets that may have happened in the past. The shape and size of the rings, as well as the composition of the material, offers an indication about the type of event that formed them.


Royal Astronomical Society

The first ever exoplanets were discovered 30 years ago around a rapidly rotating star, called a pulsar. Now, astronomers have revealed that these planets may be incredibly rare. The processes that cause planets to form, and survive, around pulsars are currently unknown. A survey of 800 pulsars followed by the Jodrell Bank Observatory over the last 50 years has revealed that this first detected exoplanet system may be extraordinarily uncommon: less than 0.5% of all known pulsars could host Earth-mass planets. Pulsars are a type of neutron star, the densest stars in the Universe, born during powerful explosions at the end of a typical star's life. They are exceptionally stable, rapidly rotating, and have incredibly strong magnetic fields. Pulsars emit beams of bright radio emission from their magnetic poles that appear to pulse as the star rotates. In 1992, the first ever exoplanets were discovered orbiting a pulsar called PSR B1257+12. The planetary system is now known to host at least three planets similar in mass to the rocky planets in our Solar System. Since then, a handful of pulsars have been found to host planets. However, the extremely violent conditions surrounding the births and lives of pulsars make 'normal' planet formation unlikely, and many of these detected planets are exotic objects (such as planets made mostly of diamond) unlike those we know in our Solar System. A team of astronomers at the University of Manchester performed the largest search for planets orbiting pulsars to date. In particular, the team looked for signals that indicate the presence of planetary companions with masses up to 100 times that of the Earth, and orbital time periods between 20 days and 17 years. Of the 10 potential detections, the most promising is the system PSR J2007+3120 with the possibility of hosting at least two planets, with masses a few times bigger than the Earth, and orbital periods of 1.9 and ~3.6 years. The results of the work indicate no bias for particular planet masses or orbital periods in pulsar systems. However, the results do yield information of the shape of these planets' orbits: in contrast to the near-circular orbits found in our Solar System, these planets would orbit their stars on highly elliptical paths. This indicates that the formation process for pulsar-planet systems is vastly different than traditional star-planet systems.



The ultra-powerful James Webb Space Telescope will catch a glimpse of the enigmatic atmosphere of a terrestrial (Earth-sized) exoplanet known as Gliese 486 b, previously termed as a “Rosetta Stone” because it could unlock the secrets of habitable. Gliese 486 b is probably not habitable in itself, but will serve as a proving ground for planets that may be. We usually define "habitable" as a rocky world that could host liquid water on its surface, although the picture is … complicated. The odd behaviour of parent red dwarf stars like Gliese 486 — popular planet-seeking targets due to their relative small size and lack of stray light interfering with observations — might shoot out a lot of life-harming radiation, for a start. We also know little about the composition of rocky planet atmospheres like Gliese 486 b, although we can make educated guesses from models and from what we can observe in planets and moons in our own Solar System. Happily, however, Webb's high-resolution view gives us a serious chance at learning about the complex environment of this exoplanet. Perched at Lagrange Point 2, Webb has an 18-segment hexagonal mirror optimized for deep space operations. The huge mirror and lack of stray light will at last allow astronomers to probe the transient molecules of gas visible in a distant, tiny planet like Gliese 486 b.

Gliese 486 b is close enough to its parent star that investigators suspect one side is permanently facing its star. Gravitational interactions between the planet and the sun – similar to the Earth and the Moon – lock the planet into a synchronous rotation with the star during Gliese 486 b's orbit. Investigators will watch as the planet passes behind its parent star, from Earth's perspective. That will allow them the best view possible of the "dayside" of the star, as this spot will be shining for Webb to observe during some of this time. Gliese 486 b is a perfect target for such an observation as it is quite hot and orbits a relatively small star, which will make its light easier to distinguish from any stellar interference. If this testbed for atmospheric observations work, the implications are huge as Webb prepares for another 20 years of operations. Secondary eclipse techniques seem to fit the bill of efficient observing, from what the team can deduce, while still being scientifically effective. "The idea here is that a planet without an atmosphere will be relatively hot, because this planet is expected to have one hemisphere — the day side — that constantly faces the star. With no atmosphere, rocks would heat up to searing temperatures visible from afar. With an atmosphere, however, the planet's dayside would be much cooler — perhaps due to highly reflective clouds that reflect away starlight, or through circulating heat to the nightside. Deductions about the planet's atmosphere would thus be visible through temperature — above a certain threshold, there likely would be no atmosphere. Webb, happily, is optimized to look in the mid-infrared wavelengths needed to assess Gliese 486 b's atmosphere or lack thereof. Coupled with its high resolution, Webb would be able to deduce the spectra or "signatures" of different gases through the telescope's spectrometers, "to try and understand what the atmosphere is made of," Mansfield said.

That Gliese 486 b is rocky is not in dispute, as eclipse observations from NASA's Transiting Exoplanet Survey Satellite coupled with radial velocity measurements from ground telescopes show a mass within the range of a rocky planet. Webb, however, will finally be able to deduce more of the planet's nature — especially because most planets emit their light in mid-infrared at five to 14 microns, precisely where the telescope is optimized to see. Webb will also allow for a large span of wavelengths to be observed at one time, giving investigators the best chance possible of spotting the unique fingerprint a gas shows in its spectrum. If Gliese 486 b has an atmosphere at its close orbital distance, there might be hope for planets in the habitable region of stars that are also red dwarfs. Flaring dwarfs might strip gas from planets' atmosphere with their radiation, making it difficult for scientists to assess whether planets might be able to hold on to their atmospheres long enough for life to develop. Even if the atmosphere isn't apparent, it still will be an exciting find as scientists will be gazing directly at the surface of a small, rocky world from afar. In that case, we will have a chance to do exo-geology', and try and figure out what types of rock the surface of the planet is made of.



In recent years, a large number of exoplanets have been found around single ‘normal’ stars. New research shows that there may be exceptions to this trend. Researchers suggest a new way of detecting dim bodies, including planets, orbiting exotic binary stars known as Cataclysmic Variables (CVs). CVs are binary star systems in which the two stars are in extremely close proximity to each other; so close that the less massive object transfers mass to the more massive. CVs are typically formed of a small, cool type of star known as a red dwarf star, and a hot, dense star – a white dwarf. Red dwarf stars have a mass between 0.07 and 0.30 solar masses and a radius of around 20% of the Sun’s, while white dwarf stars have a typical mass of around 0.75 Solar masses and a very small radius similar to that of planet Earth. In the CV system, the transfer of matter from the small star forms an accretion disk around the compact, more massive star. The brightness of a CV system mainly comes from this disk, and overpowers the light coming from the two stars. A third dim body orbiting a CV can influence the mass transfer rate between the two stars, and hence the brightness of the entire system.  The method described in the new work is based on the change of brightness in the accretion disk due to perturbations of the third body that orbits around the inner two stars.

In their research, astronomers have estimated the mass and distance of a third body orbiting four different CVs using the changes in the brightness of each system. According to calculations carried out by the team, such brightness variations have very long periods in comparison to the orbital periods in the triple system. Two out of the four CVs appear to have bodies resembling planets in orbit around them. The work has proven that a third body can perturb a cataclysmic variable in such a way that can induce changes in brightness in the system. These perturbations can explain both the very long periods that have been observed - between 42 and 265 days- and the amplitude of those changes in brightness. Of the four systems studied, observations suggest that two of the four have objects of planetary mass in orbit around them. The scientists believe that this is a promising new technique for finding planets in orbit around binary star systems, adding to the thousands already found in the last three decades.


Kavli Institute for the Physics and Mathematics of the Universe

A team of astronomers has discovered a mysterious short-duration astronomical event, or transient, that is as bright as a superluminous supernova, but evolving much faster. The Universe is full of energetic transient phenomena, astronomical events that occur over a short period of time. For example, most massive stars end their lives by exploding spectacularly, known as a supernova, a major type of transients. In order to understand the origin of these transient phenomena, various time-domain surveys have been carried out in the past few decades. As more and more transients have been discovered, researchers began noticing some new transient types in recent years. To figure out the nature of various transient phenomena, an international transient survey project called "MUltiband Subaru Survey for Early-phase Supernovae" (MUSSES). By carrying out consecutive Subaru/HSC observations in December 2020, 20 fast-evolving transients have been discovered, and one of them, MUSSES2020J (AT 2020afay), caught the team’s attention. The data has stimulated intensive discussion about the origins of MUSSES2020J and a few other FBUTs, led by various researchers within the team. The theoretical investigation is still ongoing, but the team has so far narrowed down the possibilities to a few scenarios, most of which involve an active compact object -- either a black hole or a highly magnetized neutron star -- to power these extremely bright objects. There is almost no doubt that an active compact object is involved, and it is a main reason why these transients are so different from normal supernovae.

The remaining possibilities are an event where a star is tidally disrupted by a massive black hole, or a massive star collapse which is different from normal supernovae in a sense that it has probably left a highly active compact object like an accreting black hole. The very early-phase data provided for the first time for a class of FBUTs hints the existence of sub-relativistic outflow distinctly from a bulk of the slower ejecta, and this must be a key to solving the problem. We are currently checking the details of each model to robustly identify the origin of MUSSES2020J, with the strong constraint provided by this new observation. MUSSES2020J shows a similar light curve of AT 2018cow. The light curve of AT 2018cow is well-reproduced by the model of interaction between circumstellar matter and the ejecta of a pulsational pair-instability supernova (PPISN). The PPISN is the explosion of a very massive star which would collapse to form a black hole and eject the outer layer in a jet-like form. Therefore, it is possible that a similar PPISN model with a different amount of circumstellar matter can also explain the light curve of MUSSES2020J.


Dartmouth College

Black holes with varying light signatures but that were thought to be the same objects being viewed from different angles are actually in different stages of the life cycle, according to a new study. The research on black holes known as "active galactic nuclei," or AGNs, says that it definitively shows the need to revise the widely used "unified model of AGN" that characterizes supermassive black holes as all having the same properties. Supermassive black holes are believed to reside at the centre of nearly all large galaxies, including the Milky Way. The objects devour galactic gas, dust and stars, and they can become heavier than small galaxies. For decades, researchers have been interested in the light signatures of active galactic nuclei, a type of supermassive black hole that is "accreting," or in a rapid growth stage. Beginning in the late 1980s, astronomers realized that light signatures coming from space ranging from radio wavelengths to X-rays could be attributed to AGNs. It was assumed that the objects usually had a doughnut-shaped ring -- or "torus" -- of gas and dust around them. The different brightness and colours associated with the objects were thought to be the result of the angle from which they were being observed and how much of the torus was obscuring the view. From this, the unified theory of AGNs became the prevalent understanding. The theory guides that if a black hole is being viewed through its torus, it should appear faint. If it is being viewed from below or above the ring, it should appear bright. According to the current study, however, the past research relied too heavily on data from the less obscured objects and skewed research results.

The new study focuses on how quickly black holes are feeding on space matter, or their accretion rates. The research found that the accretion rate does not depend upon the mass of a black hole, it varies significantly depending on how obscured it is by the gas and dust ring. The result shows that the amount of dust and gas surrounding an AGN is directly related to how much it is feeding, confirming that there are differences beyond orientation between different populations of AGNs. When a black hole is accreting at a high rate, the energy blows away dust and gas. As a result, it is more likely to be unobscured and appear brighter. Conversely, a less active AGN is surrounded by a denser torus and appears fainter. The study stems from a decade-long analysis of nearby AGNs detected by Swift-BAT, a high-energy NASA X-ray telescope. The telescope allows researchers to scan the local Universe to detect obscured and unobscured AGNs. The research is the result of an international scientific collaboration -- the BAT AGN Spectroscopic Survey (BASS) -- that has been working over a decade to collect and analyze optical/infrared spectroscopy for AGN observed by Swift BAT. According to the paper, by knowing a black hole's mass and how fast it is feeding, researchers can determine when most supermassive black holes underwent most of their growth, thus providing valuable information about the evolution of black holes and the Universe. Future research could include focusing on wavelengths that allow the team to search beyond the local Universe. In the nearer term, the team would like to understand what triggers AGNs to go into high accretion mode, and how long it takes rapidly accreting AGNs to transition from heavily obscured to unobscured.


Ars Technica

Data from the Webb Space Telescope has only arrived into the hands of astronomers over the last few weeks, but they've been waiting for years for this, and apparently had analyses set to go. The result has been something like a race back in time, as new discoveries find objects that formed ever closer to the Big Bang that produced our Universe. Just recently, one of these searches turned up a galaxy that was present less than 400 million years after the Big Bang. This week, a new analysis has picked out a galaxy as it appeared only 233 million years after the Universe popped into existence. The discovery is a happy byproduct of work that was designed to answer a more general question: How many galaxies should we expect to see at different time points after the Big Bang? The e early Universe was opaque to light at any wavelengths that carry more energy than is needed to ionize hydrogen. That energy is in the UV portion of the spectrum, but the red shift caused by 13 billion years of an expanding Universe has shifted that cut-off point into the infrared portion of the spectrum. To find galaxies from this time, we have to look for objects that aren't visible at shorter infrared wavelengths (meaning that light was once above the hydrogen cut-off), but do appear at lower-energy wavelengths. The deeper into the infrared the boundary between invisible and visible is, the stronger the redshift, and the more distant the object is. The more distant the object, the closer in time it is to the Big Bang. Studies of these galaxies can tell us something about their individual properties. But identifying a large collection of early galaxies can help us determine how quickly they formed and identify any changes in galaxy dynamics that happened at a specific time in the Universe's past. This change over time in the frequency of visible objects is called a "luminosity function," and some work has been done to characterize the luminosity function of early galaxies. But the infrared wavelengths of the earliest galaxies are absorbed by Earth's atmosphere, and so have to be imaged from space.

The researchers used two data sources to reconstruct the galaxies' appearances at different points in time. One was produced by analyzing work done with a ground-based infrared telescope (the ESA's VISTA telescope) and the Spitzer space telescope, both of which imaged galaxies that were relatively older when they produced the light that's now reaching Earth—about 600 million years or more after the Big Bang. The other involved data generated by the Webb, including those data sets analyzed in the paper we reported on and an area imaged in the first public photo release. In all cases, the researchers searched for the same thing: objects that were present at longer infrared wavelengths but absent from shorter ones.  Overall, the team identified 55 distant galaxies, 44 of which had never been noted previously. Thirty-nine of these come from the Webb data, and that figure included the two ancient galaxies that were identified last week. The numbers aren't especially precise at higher redshifts, where they're based on just one or two galaxies. But overall, the trend suggests a gradual decline in visible objects out to within a few hundred million years of the Big Bang, with no sharp changes or cutoffs.

But the striking thing is that there is data for a galaxy at an extremely large redshift (z = 16.7 which  places it at less than 250 million years after the Big Bang. That distance is based partly on the fact that the first wavelength filter in which the object appears shows it to be very dim there, suggesting that it is faint at the wavelengths the filter lets through. That suggests that the light cutoff generated by hydrogen is near the edge of the filter's range.  Like the distant galaxies described last week, it also appears to have the equivalent of a billion Suns of material in the form of stars. The researchers estimate that it might have started star formation as early as 120 million years after the Big Bang, and had certainly done so by 220 million years.  The researchers are pretty confident that this new galaxy represents a real finding: "Having searched extensively, we are currently unable to find any plausible explanation for this object, other than a galaxy at a new redshift record." And by adding a second independent confirmation of the earlier galaxy finds, it greatly increases the confidence we have in those discoveries. All of which indicates the new telescope is delivering as promised, at least in terms of early galaxies. 


Live Science

Since launching on Dec. 25, 2021, NASA's James Webb Space Telescope (JWST) has been pelted by at least 19 tiny space rocks — including one large one that left noticeable damage on one of the telescope's 18 gold-plated mirrors. The impact — which likely occurred between May 23 and May 25 this year — left "uncorrectable" damage to a tiny portion of that mirror, the report says. However, this little dent doesn't seem to have inhibited the telescope's performance at all. In fact, the JWST's performance is exceeding expectations "almost all across the board." Tiny rocks known as micrometeoroids are an all-too-familiar threat to spacecraft in near-Earth orbit. The U.S. Space Surveillance Network keeps track of more than 23,000 pieces of orbital debris measuring larger than the size of a softball — however, the millions of nearby space chunks that are smaller than that are almost impossible to monitor. Instead, NASA and other space agencies plan for unavoidable impacts. So far, six micrometeoroids have left noticeable "deformities" on the JWST's mirrors, amounting to about one noticeable impact per month since the telescope launched. That's all within the realm of the expected. When building the JWST, engineers intentionally hit mirror samples with micrometeoroid-sized objects to test how such impacts would affect the telescope's performance. What was unexpected, however, was the size of the larger impactor that dented the C3 mirror. This space rock was seemingly larger than the team had prepared for, and researchers are now trying to assess the impact that further strikes like this could have on the JWST.
The Laughter Zone / Re: hot weather
« Last post by Clive on July 29, 2022, 07:51 »
The Laughter Zone / Re: hot weather
« Last post by Den on July 28, 2022, 21:56 »
I told you I was not stupid, over the last week I have sold 11 of them to neighbours.  :D
Science & Nature / Mid July Astronomy Bulletin
« Last post by Clive on July 17, 2022, 11:10 »

Southwest Research Institute

Scientists combined data from NASA's New Horizons mission with novel laboratory experiments and exospheric modelling to reveal the likely composition of the red cap on Pluto's moon Charon and how it may have formed. This first-ever description of Charon's dynamic methane atmosphere using new experimental data provides a fascinating glimpse into the origins of this moon's red spot as described in two recent papers. Soon after the 2015 encounter, New Horizons scientists proposed that a reddish "tholin-like" material at Charon's pole could be synthesized by ultraviolet light breaking down methane molecules. These are captured after escaping from Pluto and then frozen onto the moon's polar regions during their long winter nights. Tholins are sticky organic residues formed by chemical reactions powered by light, in this case the Lyman-alpha ultraviolet glow scattered by interplanetary hydrogen molecules. The team realistically replicated Charon surface conditions at SwRI's new Center for Laboratory Astrophysics and Space Science Experiments (CLASSE) to measure the composition and color of hydrocarbons produced on Charon's winter hemisphere as methane freezes beneath the Lyman-alpha glow. The team fed the measurements into a new atmospheric model of Charon to show methane breaking down into residue on Charon's north polar spot. The team input the results from SwRI's ultra-realistic experiments into the atmospheric model to estimate the distribution of complex hydrocarbons emerging from methane decomposition under the influence of ultraviolet light. The model has polar zones primarily generating ethane, a colourless material that does not contribute to a reddish colour. The team think ionizing radiation from the solar wind decomposes the Lyman-alpha-cooked polar frost to synthesize increasingly complex, redder materials responsible for the unique albedo on this enigmatic moon, Ethane is less volatile than methane and stays frozen to Charon's surface long after spring sunrise. Exposure to the solar wind may convert ethane into persistent reddish surface deposits contributing to Charon's red cap.



Astronomers have unveiled intricate details of the star-forming region 30 Doradus, also known as the Tarantula Nebula, using new observations from the Atacama Large Millimeter/submillimeter Array (ALMA). In a high-resolution image released by the European Southern Observatory (ESO) and including ALMA data, we see the nebula in a new light, with wispy gas clouds that provide insight into how massive stars shape this region. These fragments may be the remains of once-larger clouds that have been shredded by the enormous energy being released by young and massive stars, a process dubbed feedback. Astronomers originally thought the gas in these areas would be too sparse and too overwhelmed by this turbulent feedback for gravity to pull it together to form new stars. But the new data also reveal much denser filaments where gravity’s role is still significant. The results imply that even in the presence of very strong feedback, gravity can exert a strong influence and lead to a continuation of star formation. Located in the Large Magellanic Cloud, a satellite galaxy of our own Milky Way, the Tarantula Nebula is one of the brightest and most active star-forming regions in our galactic neighbourhood, lying about 170 000 light-years away from Earth. At its heart are some of the most massive stars known, a few with more than 150 times the mass of our Sun, making the region perfect for studying how gas clouds collapse under gravity to form new stars.

What makes 30 Doradus unique is that it is close enough for us to study in detail how stars are forming, and yet its properties are similar to those found in very distant galaxies, when the Universe was young. Thanks to 30 Doradus, we can study how stars used to form 10 billion years ago when most stars were born. While most of the previous studies of the Tarantula Nebula have focused on its centre, astronomers have long known that massive star formation is happening elsewhere too. To better understand this process, the team conducted high-resolution observations covering a large region of the nebula. Using ALMA, they measured the emission of light from carbon monoxide gas. This allowed them to map the large, cold gas clouds in the nebula that collapse to give birth to new stars — and how they change as huge amounts of energy are released by those young stars. The new research contains detailed clues about how gravity behaves in the Tarantula Nebula’s star-forming regions, but the work is far from finished.


Association of Universities for Research in Astronomy (AURA)

An unusual ultra-faint dwarf galaxy has been discovered on the outer fringes of the Andromeda Galaxy thanks to an amateur astronomer examining archival data processed by NSF's NOIRLab's Community Science and Data Center. Follow-up by professional astronomers using the International Gemini Observatory, a Program of NSF's NOIRLab, revealed that the dwarf galaxy -- Pegasus V -- contains very few heavier elements and is likely to be a fossil of the first galaxies. The faintest galaxies are considered to be fossils of the very first galaxies that formed, and these galactic relics contain clues about the formation of the earliest stars. While astronomers expect the Universe to be teeming with faint galaxies like Pegasus V, they have not yet discovered nearly as many as their theories predict. If there are truly fewer faint galaxies than predicted this would imply a serious problem with astronomers' understanding of cosmology and dark matter. Discovering examples of these faint galaxies is therefore an important endeavour, but also a difficult one. Part of the challenge is that these faint galaxies are extremely tricky to spot, appearing as just a few sparse stars hidden in vast images of the sky. The strong concentration of old stars that the team found in Pegasus V suggests that the object is likely a fossil of the first galaxies. When compared with the other faint galaxies around Andromeda, Pegasus V seems uniquely old and metal-poor, indicating that its star formation ceased very early indeed. Upcoming astronomical facilities are set to shed more light on faint galaxies. Pegasus V was witness to a time in the history of the Universe known as reionization, and other objects dating back to this time will soon be observed with NASA's James Webb Space Telescope. Astronomers also hope to discover other such faint galaxies in the future using Vera C. Rubin Observatory, a Program of NSF's NOIRLab. Rubin Observatory will conduct an unprecedented, decade-long survey of the optical sky called the Legacy Survey of Space and Time (LSST).


University of Cologne

Researchers have discovered the fastest known star, which travels around a black hole in record time. The star, S4716, orbits Sagittarius A*, the black hole in the centre of our Milky Way, in four years and reaches a speed of around 8000 kilometres per second. S4716 comes as close as 100 AU (astronomical unit) to the black hole -- a small distance by astronomical standards. In the vicinity of the black hole at the centre of our galaxy is a densely packed cluster of stars. This cluster, called S cluster, is home to well over a hundred stars that differ in their brightness and mass. S stars move particularly fast. By means of continuously refining methods of analysis, together with observations covering almost twenty years, the scientist now identified without a doubt a star that travels around the central supermassive black hole in just four years. A total of five telescopes observed the star, with four of these five being combined into one large telescope to allow even more accurate and detailed observations.Moreover, the discovery sheds new light on the origin and evolution of the orbit of fast-moving stars in the heart of the Milky Way. 'The short-period, compact orbit of S4716 is quite puzzling. Stars cannot form so easily near the black hole. S4716 had to move inwards, for example by approaching other stars and objects in the S cluster, which caused its orbit to shrink significantly.


Waseda University

As telescopes have become more advanced and powerful, astronomers have been able to detect more and more distant galaxies. These are some of the earliest galaxies to form in our Universe that began to recede away from us as the Universe expanded. In fact, the more the distance, the faster a galaxy appears to move away from us. Interestingly, we can estimate how fast a galaxy is moving, and in turn, when it was formed based on how "redshifted" its emission appears. This is similar to a phenomenon called "Doppler effect," where objects moving away from an observer emit the light that appears shifted towards longer wavelengths (hence the term "redshift") to the observer. The Atacama Large Millimeter/submillimeter Array (ALMA) telescope located in the midst of the Atacama Desert in Chile is particularly well-suited for observing such redshifts in galaxy emissions. Recently, a team of researchers has observed redshifted emissions of a distant galaxy, MACS1149-JD1 (hereafter JD1), which has led them to some interesting conclusions. Beyond finding very distant, galaxies, studying their internal motion of gas and stars provides motivation for understanding the process of galaxy formation in the earliest possible Universe. Galaxy formation begins with the accumulation of gas and proceeds with the formation of stars from that gas. With time, star formation progresses from the centre outward, a galactic disk develops, and the galaxy acquires a particular shape. As star formation continues, newer stars form in the rotating disk while older stars remain in the central part. By studying the age of the stellar objects and the motion of the stars and gas in the galaxy, it is possible to determine the stage of evolution the galaxy has reached.

Conducting a series of observations over a period of two months, the astronomers successfully measured small differences in the "redshift" from position to position inside the galaxy and found that JD1 satisfied the criterion for a galaxy dominated by rotation. Next, they modelled the galaxy as a rotating disk and found that it reproduced the observations very well. The calculated rotational speed was about 50 kilometres per second, which was compared to the rotational speed of the Milky Way disk of 220 kilometres per second. The team also measured the diameter of JD1 at only 3,000 light-years, much smaller than that of the Milky Way at 100,000 light-years across. The significance of their result is that JD1 is by far the most distant and, therefore, earliest source yet found that has a rotating disk of gas and stars. Together with similar measurements of nearer systems in the research literature, this has allowed the team to delineate the gradual development of rotating galaxies over more than 95% of our cosmic history. Furthermore, the mass estimated from the rotational speed of the galaxy was in line with the stellar mass previously estimated from the galaxy's spectral signature, and came predominantly from that of "mature" stars that formed about 300 million years ago. This shows that the stellar population in JD1 formed at an even earlier epoch of the cosmic age. The rotation speed of JD1 is much slower than those found in galaxies in later epochs and our Galaxy and it is likely that JD1 is at an initial stage of developing a rotational motion.


California Institute of Technology

Sometime around 400 million years after the birth of our Universe, the first stars began to form. The Universe's so-called dark ages came to an end and a new light-filled era began. More and more galaxies began to take shape and served as factories for churning out new stars, a process that reached a peak about 4 billion years after the Big Bang. Luckily for astronomers, this bygone era can be observed. Distant light takes time to reach us, and our telescopes can pick up light emitted by galaxies and stars billions of years ago (our Universe is 13.8 billion years old). But the details of this chapter in our Universe's history are murky since most of the stars being formed are faint and hidden by dust. A new Caltech project, called COMAP (CO Mapping Array Project), will offer us a new glimpse into this epoch of galaxy assembly, helping to answer questions about what really caused the Universe's rapid increase in the production of stars. The current phase of the project uses a 10.4-meter "Leighton" radio dish at OVRO to study the most common kinds of star-forming galaxies spread across space and time, including those that are too difficult to view in other ways because they are too faint or hidden by dust. The radio observations trace the raw material from which stars are made: cold hydrogen gas. This gas is not easy to pinpoint directly, so instead COMAP measures bright radio signals from carbon monoxide (CO) gas, which is always present along with the hydrogen. COMAP's radio camera is the most powerful ever built to detect these radio signals. The first science results from the project have just been published in seven papers in The Astrophysical Journal. Based on observations taken one year into a planned five-year survey, COMAP set upper limits on how much cold gas must be present in galaxies at the epoch being studied, including the ones that are normally too faint and dusty to see. While the project has not yet made a direct detection of the CO signal, these early results demonstrate that it is on track to do so by the end of the initial five-year survey and ultimately will paint the most comprehensive picture t of the Universe's history of star formation. COMAP works by capturing blurry radio images of clusters of galaxies over cosmic time rather than sharp images of individual galaxies. This blurriness enables the astronomers to efficiently catch all the radio light coming from a larger pool of galaxies, even the faintest and dustiest ones that have never been seen.



Human and machine intelligence worked together to find 40,000 ring galaxies. Galaxies live a chaotic life. Collisions with other galaxies and bursts of energy from supermassive black holes disrupt the colours and orbits of billions of stars, leaving tell-tale markers that volunteers search for on the Galaxy Zoo website. But understanding exactly which cosmic events lead to which markers requires millions of measured images - more than humans could ever search. To help, researchers used a decade of Galaxy Zoo volunteer measurements (totalling over 96 million clicks) to create an automatic assistant - a new AI algorithm. The algorithm, affectionately named “Zoobot”, can not only accurately predict what volunteers would say but understands where it might be mistaken.

The discovery of 40,000 rare ring-shaped galaxies is six times more than previously known. Rings take billions of years to form and are destroyed in galaxy-galaxy collisions, and so this giant new sample will help reveal how isolated galaxies evolve. The dataset will also tell scientists how galaxies age more generally. Zoobot is designed to be retrained again and again for new science goals. Just like a musician can learn a new instrument faster than their first instrument, Zoobot can learn to answer new shape questions easily because it has already learned to answer more than 50 different questions. Galaxy Zoo turns 15 years old this week, and we are still innovating. The work Dr Walmsley is leading will make it possible for a new generation of discoveries to be made from upcoming large galaxy surveys.”


New York University

A team of physicists has developed a method for predicting the composition of dark matter -- invisible matter detected only by its gravitational pull on ordinary matter and whose discovery has been long sought by scientists. Its work centres on predicting "cosmological signatures" for models of dark matter with a mass between that of the electron and the proton. Previous methods had predicted similar signatures for simpler models of dark matter. This research establishes new ways to find these signatures in more complex models, which experiments continue to search for, the paper's authors note.  In the research, scientists focused on big bang nucleosynthesis (BBN) -- a process by which light forms of matter, such as helium, hydrogen, and lithium, are created. The presence of invisible dark matter affects how each of these elements will form. Also vital to these phenomena is the cosmic microwave background (CMB) -- electromagnetic radiation, generated by combining electrons and protons, that remained after the universe's formation. The team sought a means to spot the presence of a specific category of dark matter -- that with a mass between that of the electron and the proton -- by creating models that took into account both BBN and CMB. In its research, the team made predictions of cosmological signatures linked to the presence of certain forms of dark matter. These signatures are the result of dark matter changing the temperatures of different particles or altering how fast the Universe expands. Their results showed that dark matter that is too light will lead to different amounts of light elements than what astrophysical observations see.



NASA has announced that the Psyche asteroid mission, the agency’s first mission designed to study a metal-rich asteroid, will not make its planned 2022 launch attempt. Due to the late delivery of the spacecraft’s flight software and testing equipment, NASA does not have sufficient time to complete the testing needed ahead of its remaining launch period this year, which ends on Oct. 11. The mission team needs more time to ensure that the software will function properly in flight. NASA selected Psyche in 2017 as part of the agency’s Discovery Program, a line of low-cost, competitive missions led by a single principal investigator. The agency is forming an independent assessment team to review the path forward for the project and for the Discovery Program. The mission’s 2022 launch period, which ran from Aug. 1 through Oct. 11, would have allowed the spacecraft to arrive at the asteroid Psyche in 2026. There are possible launch periods in both 2023 and 2024, but the relative orbital positions of Psyche and Earth mean the spacecraft would not arrive at the asteroid until 2029 and 2030, respectively. The exact dates of these potential launch periods are yet to be determined. Two ride-along projects were scheduled to launch on the same SpaceX Falcon Heavy rocket as Psyche, including NASA’s Janus mission to study twin binary asteroid systems, and the Deep Space Optical Communications technology demonstration to test high-data-rate laser communications that is integrated with the Psyche spacecraft. NASA is assessing options for both projects.
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