Topic: Late January Astronomy Bulletin

[Clive]

ANCIENT ICE REVEALS 9,000 YEAR-OLD SOLAR STORM

Lund University

Through analysis of ice cores from Greenland and Antarctica, a research team has found evidence of an extreme solar storm that occurred about 9,200 years ago. What puzzles the researchers is that the storm took place during one of the Sun's more quiet phases -- during which it is generally believed our planet is less exposed to such events. The Sun is a prerequisite for life on Earth. But our life-giving companion can also cause problems. When there is strong activity on the surface of the Sun, more energy is released, something that can give rise to geomagnetic storms. This in turn can cause power outages and communication disturbances. Predicting solar storms is difficult. It is currently believed that they are more likely during an active phase of the Sun, or solar maximum, during the so-called sunspot cycle. The researchers scoured the drill cores for peaks of the radioactive isotopes beryllium-10 and chlorine-36. These are produced by high-energy cosmic particles that reach Earth, and can be preserved in ice and sediment. If a similar solar storm were to take place today, it could have devastating consequences. In addition to power outages and radiation damage to satellites, it could pose a danger to air traffic and astronauts as well as a collapse of various communication systems.

FAR SIDE OF MOON HAS STICKIER SOIL

Science Daily

China's lunar rover Yutu-2 is part of the longest lunar surface mission in history, having landed on the far side of the Moon three years ago. The team behind the mission recently provided an update on the rover's findings by way of a paper published in Science Robotics. Since it landed, the rover has travelled 1,005 metres, part of which was to investigate an oddly-shaped "mystery hut", which predictably didn't turn out to be aliens. The rover is part of the Chang'e-4 mission, which was the first to land on the far side of the Moon when it reached our celestial neighbour in January 2019. A year later, in January 2020, the mission released a wealth of images of the far side of the Moon. The mission's main aim is to study the composition of volcanic rocks on the far side of the Moon to the more extensive samples taken of those on the near side. The latest update provides an interesting comparison between the composition — to be precise, the stickiness — of the soil on the near and the far side of the Moon. One of the findings the Yutu-2 outlined in their new paper was that soil appears to be stickier on the far side of the Moon. The team made this discovery when they saw that lunar soil was sticking to Yutu-2's wheels much more than it has been observed to do so on rovers on the near side of the Moon. The "cloddy soil sticking on [Yutu-2's] wheels implies a greater cohesion of the lunar soil than encountered at other lunar landing sites. Further identification results indicate that the regolith resembles dry sand and sandy loam on Earth in bearing properties, demonstrating greater bearing strength than that identified during the Apollo missions." Interestingly, the team also pointed out that their new findings "may lead to locomotion with improved efficiency and larger range," suggesting that future missions to the far side of the Moon could have rovers specially designed based on the new findings on the composition of the terrain.

Yutu-2 also discovered 88 craters, 57 of which were less than 10 metres across. Only two of these were more than 60 metres across. Based on the relatively small size of the majority of these craters, the researchers believe they may be secondary craters of the larger Zhinyu crater near the rover's landing location. China's Chang'e-5 mission recently detected water from the lunar surface for the first time in history, and China's space agency also recently announced it was building a fission reactor for the Moon that would be roughly 100 times more powerful than one being built by NASA. China's Chang'e-4 mission, and the subsequent Chang'e-5 mission, are part of the country's ambitious plans to catch up with the achievements of the U.S. and Russia in space to position itself as one of the world's spacefaring superpowers.

ASTEROID COULD BE UNSEEN BECAUSE OF BLIND SPOT

Icarus

Huge asteroids could be heading for Earth totally undetected due to a blind spot in the sky. Astronomers have found objects heading towards us at nighttime from the east can appear stationary because of the way our planet rotates and orbits the Sun. It means they can bypass the extensive network of computerised telescopes and “sneak up” on Earth without warning. The telescopes algorithm has been created to be on alert for asteroids and so flags up moving objects, to avoid false alarms when supernovae and flare stars pass. They are programmed to consider that objects heading towards Earth seem to drift west in the sky due to the planet’s eastward spin on its axis. But when asteroids approach from the eastern sky, Earth’s spin and curved orbit around the Sun can make the objects appear stationary. The revelation explained that 50 per cent of impactors heading to Earth from the east are thought to experience periods of slow motion, making them hard to detect. The team wrote: “Surveys should take extra care when surveying the sky in this direction, and aggressively follow up new slow-moving objects.” But despite the alarming revelation the University of Hawaii, said people “shouldn’t lose sleep” over the prospects of being caught off guard by an asteroid. It should be possible to update the algorithms to overcome the seemingly stationary effect. In 2019, Earth had a “near miss” when a 100 metre asteroid darted past the planet only 43,000 miles away. After being spotted just 24 hours earlier, it sparked concerns across the astronomical community and led to a revamp of guidelines for asteroid observers. NASA were then tasked with identifying 90 per cent of asteroids that are bigger than 140 metres and could wipe out a large city if it landed by the US Congress. A heavy spaceship program was also launched last year to smash into the moonlet of a comet to knock it off course. Around 40 per cent of large asteroids that are closely approaching Earth have been catalogued. Once we have catalogued more than 90%, the number that can creep up on us from this direction will be small. There is no known threat of an asteroid colliding with Earth in the next century. The most hazardous asteroid in the solar system has been named Bennu and there is a one in 1,750 chance of it striking Earth in the next 200 years.

MARTIAN METEORITE'’S ORGANIC MATERIAL NOT BIOLOGICAL

Carnegie Institution for Science

Organic molecules found in a meteorite that hurtled to Earth from Mars were synthesized during interactions between water and rocks that occurred on the Red Planet about 4 billion years ago, according to new analysis. The meteorite, called Allan Hills (ALH) 84001, was discovered in the Antarctic in 1984 and is considered one of the oldest known projectiles to reach Earth from Mars. Organic molecules contain carbon and hydrogen, and sometimes include oxygen, nitrogen, sulphur, and other elements. Organic compounds are commonly associated with life, although they can be created by non-biological processes as well, which are referred to as abiotic organic chemistry. For years, scientists have debated the origin story for the organic carbon found in the Allan Hills 84001 meteorite, with possibilities including various abiotic process related to volcanic activity, impact events on Mars, or hydrological exposure, as well as potentially the remnants of ancient life forms on Mars or contamination from its crash landing on Earth. The team used a variety of sophisticated sample preparation and analysis techniques -- including co-located nanoscale imaging, isotopic analysis, and spectroscopy -- to reveal the origin of organic molecules in the Allan Hills 84001 meteorite. They found evidence of water-rock interactions similar to those that happen on Earth. The samples indicate that the Martian rocks experienced two important geochemical processes. One, called serpentinization, occurs when iron- or magnesium-rich igneous rocks chemically interact with circulating water, changing their mineralogy and producing hydrogen in the process. The other, called carbonization, involves interaction between rocks and slightly acidic water containing dissolved carbon dioxide and results in the formation of carbonate minerals. It is unclear whether these processes were induced by surrounding aqueous conditions simultaneously or sequentially, but the evidence indicates that the interactions between water and rocks did not occur over a prolonged period. What is evident, however, is that the reactions produced organic material from the reduction of carbon dioxide.

These mineralogical features are rare in Martian meteorites, and while carbonation and serpentinization have been shown in orbital surveys of Mars and carbonation has been found in other, less-ancient, Martian meteorites, this is the first instance of these processes occurring in samples from ancient Mars. Organic molecules have been detected in other Martian meteorites and from work with the Sample Analysis at Mars (SAM) team on the Curiosity rover, indicating that abiotic synthesis of organic molecules has been a part of Martian geochemistry for much of the planet's history. The team concluded that these kinds of non-biological, geological reactions are responsible for a pool of organic carbon compounds from which life could have evolved and represent a background signal that must be taken into consideration when searching for evidence of past life on Mars. Furthermore, if these reactions happened on ancient Mars, they must have happened on ancient Earth, and could possibly explain the results from Saturn's moon Enceladus as well. All that is required for this type of organic synthesis is for a brine that contains dissolved carbon dioxide to percolate through igneous rocks. The search for life on Mars is not just an attempt to answer the question 'are we alone?' It also relates to early Earth environments and addresses the question of 'where did we come from?'

NEWLY DISCOVERED CARBON MAY YIELD CLUES TO ANCIENT MARS

Penn State

NASA's Curiosity rover landed on Mars on Aug. 6, 2012, and since then has roamed Gale Crater taking samples and sending the results back home for researchers to interpret. Analysis of carbon isotopes in sediment samples taken from half a dozen exposed locations, including an exposed cliff, leave researchers with three plausible explanations for the carbon's origin -- cosmic dust, ultraviolet degradation of carbon dioxide, or ultraviolet degradation of biologically produced methane. Carbon has two stable isotopes, 12 and 13. By looking at the amounts of each in a substance, researchers can determine specifics about the carbon cycle that occurred, even if it happened a very long time ago. The amounts of carbon 12 and carbon 13 in our solar system are the amounts that existed at the formation of the solar system. Both exist in everything, but because carbon 12 reacts more quickly than carbon 13, looking at the relative amounts of each in samples can reveal the carbon cycle. Curiosity, which is led by NASA's Jet Propulsion Laboratory in Southern California, has spent the last nine years exploring an area of Gale Crater that has exposed layers of ancient rock. The rover drilled into the surface of these layers and recovered samples from buried sedimentary layers. Curiosity heated the samples in the absence of oxygen to separate any chemicals. Spectrographic analysis of a portion of the reduced carbon produced by this pyrolysis showed a wide range of carbon 12 and carbon 13 amounts depending on where or when the original sample formed. Some carbon was exceptionally depleted in carbon 13 while other carbon samples where enriched.

To explain the exceptionally depleted samples, the researchers suggest three possibilities -- a cosmic dust cloud, ultraviolet radiation breaking down carbon dioxide, or ultraviolet degradation of biologically created methane. Every couple of hundred million years the solar system passes through a galactic molecular cloud. It doesn't deposit a lot of dust so It is hard to see any of these deposition events in the Earth record. To create a layer that Curiosity could sample, the galactic dust cloud would have first lowered the temperature on a Mars that still contained water and created glaciers. The dust would have deposited on top of the ice and would then need to remain in place once the glacier melted, leaving behind a layer of dirt that included the carbon. So far, there is limited evidence of past glaciers at Gale Crater on Mars. According to the researchers, "this explanation is plausible, but it requires additional research." A second possible explanation for lower amounts of carbon 13 is the ultraviolet conversion of carbon dioxide to organic compounds like formaldehyde. There are papers that predict that UV could cause this type of fractionation however, we need more experimental results showing this size fractionation so we can rule in or rule out this explanation. The third possible method of producing carbon 13 depleted samples has a biological basis. On Earth, a strongly carbon 13 depleted signature from a paleosurface would indicate past microbes consumed microbially produced methane. Ancient Mars may have had large plumes of methane being released from the subsurface where methane production would have been energetically favourable. Then, the released methane would either be consumed by surface microbes or react with ultraviolet light and be deposited directly on the surface. However, according to the researchers, there is currently no sedimentary evidence of surface microbes on the past Mars landscape, and so the biological explanation highlighted in the paper relies on ultraviolet light to place the carbon 13 signal onto the ground. All three possibilities point to an unusual carbon cycle unlike anything on Earth today but more data is needed to figure out which of these is the correct explanation. It would be nice if the rover would detect a large methane plume and measure the carbon isotopes from that, but while there are methane plumes, most are small, and no rover has sampled one large enough for the isotopes to be measured. Finding the remains of microbial mats or evidence of glacial deposits could also clear things up, a bit. Curiosity is still collecting and analyzing samples and will be returning to the pediment where it found some of the samples in this study in about a month.

OXYGEN IONS IN JUPITER’S INNERMOST RADIATION BELTS

Max Planck Institute for Solar System Research

Nearly 20 years after the end of NASA's Galileo mission to Jupiter, scientists in Germany have unlocked a new secret from the mission's extensive data sets. For the first time, the research team was able to determine beyond doubt that the high-energy ions surrounding the gas giant as part of its inner radiation belt are primarily oxygen and sulphur ions. They are thought to have originated in volcanic eruptions on Jupiter's moon Io. Near the orbit of the moon Amalthea, which orbits Jupiter further inward, the team discovered an unexpectedly high concentration of high-energy oxygen ions that cannot be explained by Io's volcanic activity. A previously unknown ion source must be at work here. Planets like Earth, Jupiter, and Saturn with global magnetic fields of their own are surrounded by so-called radiation belts: Trapped in the magnetic field, fast moving charged particles such as electrons, protons, and heavier ions whiz around thus forming the invisible, torus-shaped radiation belts. With their high velocities reaching almost the speed of light, the particles can ionize other molecules when they collide, creating a hazardous environment that can also be dangerous to space probes and their instruments. In this respect, the gas giant Jupiter sports the most extreme radiation belts in the Solar System. Researchers now present the most comprehensive study to date of the heavy ions in Jupiter's inner radiation belts. Like Jupiter's massive magnetic field, its radiation belts extend several million kilometres into space; however, the region within the moon's orbit of Europa, an area with a radius of about 670,000 kilometres around the gas giant, is the scene of the highest energetic particle densities and velocities. Viewed from Jupiter, Europa is the second of the four large Jovian satellites named "Galilean moons" after their 17th century discoverer. Io is the innermost Galilean moon. With the space probes Pioneer 11 in the mid-1970s, Galileo from 1995 to 2003, and currently Juno, three space missions have so far ventured into this innermost part of these radiation belts and performed in-situ measurements. Unfortunately, the data from Pioneer 11 and Juno do not allow astronomers to conclude beyond doubt what kind of ions the spacecraft encountered there, therefore their energies and origin were also unclear until now.

NASA's Galileo spacecraft reached the Jupiter system in 1995. Equipped with the Heavy Ion Counter (HIC), the mission spent the following eight years providing fundamental insights into the distribution and dynamics of charged particles around the gas giant. However, to protect the spacecraft, it initially flew solely through the outer, less extreme regions of the radiation belts. Only in 2003, shortly before the end of the mission, when a greater risk was justifiable, Galileo ventured into the innermost region within the orbits of the moons Amalthea and Thebe. Viewed from Jupiter, Amalthea and Thebe are the third and fourth moons of the giant planet. The orbits of Io and Europa lie farther outward. Because of the exposure to strong radiation, it was to be expected that the measurement data from HIC and EPD from the inner region of the radiation belt would be heavily corrupted. After all, neither of these two instruments was specifically designed to operate in such a harsh environment. The team has now been able to determine for the first time the ion composition within the inner radiation belts, as well as the ions' velocities and spatial distribution. In contrast to the radiation belts of Earth and Saturn, which are dominated by protons, the region within the orbit of Io also contains large amounts of the much heavier oxygen and sulphur ions, with oxygen ions prevailing among the two. The energy distribution of the heavy ions outside the orbit of Amalthea suggests that they are largely introduced from a more distant region of the radiation belts. The moon Io with its more than 400 active volcanoes, which repeatedly hurl large amounts of sulphur and sulphur dioxide into space, and to a lesser extent, Europa, are likely the main sources. Further inward, within Amalthea's orbit, the ion composition changes drastically in favour of oxygen. The concentration and the energy of oxygen ions there is much higher than expected. Actually, the concentration should be decreasing in this region, as the moons Amalthea and Thebe absorb incoming ions; the two small moons' orbits thus form a kind of natural ion barrier. This behaviour is, for example, known from radiation belts of the Saturnian system with its many moons. The only explanation for the increased concentration of oxygen ions is therefore another, local source in the innermost region of the radiation belts. The release of oxygen following the collisions of sulphur ions with the fine dust particles of Jupiter's rings constitute one possibility, as the researchers' computer simulations show. The rings, which are much fainter than the Saturnian ones, extend approximately as far as the orbit of Thebe. However, it is also conceivable that low-frequency electromagnetic waves in the magnetospheric environment of the innermost radiation belts heat oxygen ions to the observed energies.


 GIGANTIC PLANET HIDDEN IN PLAIN SIGHT

University of California - Riverside

Citizen scientists have discovered a giant gas planet hidden from view by typical stargazing tools. The planet, TOI-2180 b, has the same diameter as Jupiter, but is nearly three times more massive. Researchers also believe it contains 105 times the mass of Earth in elements heavier than helium and hydrogen. Nothing quite like it exists in our solar system. The planet is special because it takes 261 days to complete a journey around its star, a relatively long time compared to many known gas giants outside our solar system. Its relative proximity to Earth and the brightness of the star it orbits also make it likely astronomers will be able to learn more about it. In order to locate exoplanets, which orbit stars other than our Sun, NASA's TESS satellite looks at one part of the sky for a month, then moves on. It is searching for dips in brightness that occur when a planet crosses in front of a star. as a planet. For these reasons, TESS isn't focused on these single transit events. However, a small group of citizen scientists is. Looking over TESS data, researchers saw light dim from the TOI-2180 star, just once. Using the Lick Observatory's Automated Planet Finder Telescope, they observed the planet's gravitational tug on the star, which allowed them to calculate the mass of TOI-2180 b and estimate a range of possibilities for its orbit. Hoping to observe a second transit event, a campaign was organized using 14 different telescopes across three continents in the northern hemisphere. Over the course of 11 days in August 2021, the effort resulted in 20,000 images of the TOI-2180 star, though none of them detected the planet with confidence. However, the campaign did lead the group to estimate that TESS will see the planet transit its star again in February, when they're planning a follow up study.

EXOMOONS ARE NEXT BIG THING

Columbia University

Scientists have spotted a new candidate for a moon existing outside of our solar system, with only a 1 per cent chance the observation could be an anomaly. More than 4,000 exoplanets have been mapped since the first was found in 1992. Although the finding of worlds beyond the Earth's immediate star system generated much excitement at the time, exoplanets are not so rare a discovery in recent years. However, the existence of moons outside the solar system has yet to be confirmed. Going with the thinking that there's nothing particularly special about our own solar system, which is host to more than 200 moons, then we might assume they are also commonplace elsewhere. Scientists have put together a study of data from the Kepler space telescope, which NASA launched in 2009 and retired nine years later after it had helped discover more than 2,000 exoplanets. Given the abundance of moons in our solar system, it is reasonable to presume that exomoons will reside around some exoplanets – which has motivated efforts to detect them. The team applied various mathematical models to a pool of 73 cool giants picked as promising places to find exomoons because they are transiting planets that periodically eclipse their host star, making potential moons easier to detect. Subsequent number-crunching earmarked Kepler-1708 b-i, most probably a moon more than twice the size of Earth orbiting a Jupiter-like planet which in turn orbits a Sun-like star. Exhibiting a cautious air, the scientists also calculated that the chances of the candidate being a false-positive rather than the first confirmed exomoon was around 1 per cent.

The team can find no grounds to reject Kepler-1708 b-i as an exomoon candidate at this time, but urge both caution and further observations. Kepler-1708 b-i is not the only space object in the running to become the first confirmed exomoon. Proposed in 2018, Kepler-1625 b-i42 is another candidate, and also unexpectedly large. Although the reality of Kepler-1625 b-i remains unclear, the existence of this second candidate challenges astronomers to consider the origins of such large moons. As well as confirming the finding, further observations could help explain why such large moons appear so close to gas giants, which "certainly challenge conventional thinking. Ultimately, the reality of supermoons such as Kepler-1708 b-i and Kepler-1625 b-i will require follow-up transit photometry, as both their nature and supporting evidence demand appropriate scepticism at this time.

EXTRAORDINARY BLACK HOLE FOUND IN NEARBY GALAXY

University of Utah

Astronomers have discovered a black hole unlike any other. At one hundred thousand solar masses, it is smaller than the black holes we have found at the centres of galaxies, but bigger than the black holes that are born when stars explode. This makes it one of the only confirmed intermediate-mass black holes, an object that has long been sought by astronomers. The black hole was hidden within B023-G078, an enormous star cluster in our closest neighbouring galaxy Andromeda. Long thought to be a globular star cluster, the researchers argue that B023-G078 is instead a stripped nucleus. Stripped nuclei are remnants of small galaxies that fell into bigger ones and had their outer stars stripped away by gravitational forces. What's left behind is a tiny, dense nucleus orbiting the bigger galaxy and at the centre of that nucleus, a black hole. B023-G078 was known as a massive globular star cluster -- a spherical collection of stars bound tightly by gravity. However, there had only been a single observation of the object that determined its overall mass, about 6.2 million solar masses. With new observational data from the Gemini Observatory and images from the Hubble Space Telescope, the team calculated how mass was distributed within the object by modelling its light profile. A globular cluster has a signature light profile that has the same shape near the cenre as it does in the outer regions. B023-G078 is different. The light at the centre is round and then gets flatter moving outwards. The chemical makeup of the stars changes too, with more heavy elements in the stars at the centre than those near the object's edge.

The researchers used the object's mass distribution to predict how fast the stars should be moving at any given location within the cluster and compared it to their data. The highest velocity stars were orbiting around the centre. When they built a model without including a black hole, the stars at the centre were too slow compared their observations. When they added the black hole, they got speeds that matched the data. The black hole adds to the evidence that this object is a stripped nucleus. The researchers are hoping to observe more stripped nuclei that may hold more intermediate mass black holes. These are an opportunity to learn more about the black hole population at the centres of low-mass galaxies, and to learn about how galaxies are built up from smaller building blocks.

MONSTER BLACK HOLE 'GIVING BIRTH' TO STARS

Science Daily

Astronomers have spotted a black hole "giving birth" to stars at the centre of a nearby dwarf galaxy — and the stellar newborns are tethered to the black hole by a massive "umbilical cord" made of gas and dust. The supermassive black hole, situated roughly 34 million light-years away in the galaxy Henize 2-10, was seen spewing an enormous, 500-light-year-long jet of ionized gas from its centre at around 1.6 million km/h, contributing to a "firestorm" of new star formation in a nearby stellar nursery. The discovery, made using NASA's Hubble Space Telescope, is the first time a black hole in a dwarf galaxy (a galaxy with 1 billion or fewer stars) has been seen birthing stars. Astronomers observed the jet's thin tendril stretching out from the black hole and across space to a bright stellar nursery. Supermassive black holes — which are millions to billions the size of stellar-mass black holes — have been spotted spewing cosmic plumes before, but until now, astronomers thought that these jets hindered, rather than helped, star formation in dwarf galaxies.

Black holes make the jets that spew from them by sucking in material from nearby gas clouds or stars before slingshotting it back into space in the form of blazing plasma traveling close to the speed of light. If heated to the right temperature, the gas clouds that make contact with the jet will then become ideal nurseries for future stars. But getting to that Goldilocks zone is crucial; if the jets heat the gas clouds up too much, they can lose their ability to cool back down in the way necessary for star formation, according to NASA. But with the gentle, less-massive outflow from the black hole in Henize 2-10, gas conditions were perfect for star formation.

As this black hole has remained relatively small over time, the researchers believe that studying it in more detail could help them to understand the smaller origins of larger supermassive black holes in the Universe, and what processes made them balloon to such enormous scales. Plus, the high-resolution method the team developed to spot the black hole's dim signature can now be used to find others like it.