Topic: Mid December Astronomy Bulletin

[Clive]

SPACEFLIGHT DAMAGES LIVER METABOLISM
University of Tsukuba

The latest findings of a series of studies on mice that examined harmful effects caused by spending time in space show that gene expression related to liver metabolism is altered in response to the space environment. The benefit of these findings is that it may be possible to offset these changes with dietary supplementation during spaceflight. Like other inhabitants of this planet, humans have evolved for life on Earth, not life in space or elsewhere. During spaceflight, the human body is exposed to a harmful environment, characterized by null or microgravity and high radiation levels. The liver is affected by spaceflight more than any other organ -- its crucial role in neutralizing harmful substances in the body means that spaceflight places incredible demands on the organ. The research team conducted novel experiments to compare liver gene expression levels between mice exposed to microgravity, mice exposed to simulated gravity on the International Space Station, and mice at ground level on Earth. Mice that travelLed to space and back had a lower antioxidant capacity because they had lower levels of the sulphur-containing compounds (e.g., ergothioneine, cysteine, and glutathione) that play a role in protecting cells by reducing reactive oxygen compounds, which limits free-radical damage. Overall, many indicators of oxidative stress were evident in the livers of these mice. In addition, there was greater expression of genes related to oxidative stress and sulphur metabolism pathways (which deplete levels of sulphur-containing antioxidant compounds) in mice that had been exposed to space. Some effects, however, only occurred in mice exposed to microgravity. This research not only identifies factors that could exacerbate the likelihood of liver damage but, by clarifying the role of specific metabolic pathways, also demonstrates the potential for existing drugs or dietary supplements to be used to treat or prevent such damage as humans embark on a new era of space exploration.


LUNAR CARBON DIOXIDE COLD TRAPS CONFIRMED
American Geophysical Union

After decades of uncertainty, researchers have confirmed the existence of lunar carbon dioxide cold traps that could potentially contain solid carbon dioxide. The discovery will likely have a major influence in shaping future lunar missions and could impact the feasibility of a sustained robot or human presence on the Moon. In the permanently shadowed regions at the poles of our Moon, temperatures dip below those in the coldest areas of Pluto, allowing for carbon dioxide cold traps. In these cold traps, carbon dioxide molecules could freeze and remain in solid form even during peak temperatures in the lunar summer. Future human or robot explorers could use the solid carbon dioxide in these cold traps to produce fuel or materials for longer lunar stays. The carbon dioxide and other potential volatile organics could also help scientists better understand the origin of water and other elements on the Moon. Although cold traps have been predicted by planetary scientists for years, this new study is the first to firmly establish and map the presence of carbon dioxide cold traps. To find the coldest spots on the Moon's surface, researchers analyzed 11 years of temperature data from the Diviner Lunar Radiometer Experiment, an instrument flying aboard NASA's Lunar Reconnaissance Orbiter. The existence of carbon dioxide cold traps does not guarantee the existence of solid carbon dioxide on the Moon, but this verification does make it highly likely that future missions could find carbon dioxide ice there, according to the researchers. Carbon dioxide could be a tracer for the sources of water and other volatiles on the lunar surface, helping scientists to understand how they arrived on the Moon and on Earth.


FALSE FOSSILS COULD MISLEAD SEARCH FOR LIFE ON MARS
University of Edinburgh

Mars explorers searching for signs of ancient life could be fooled by fossil-like specimens created by chemical processes, research suggests. Rocks on Mars may contain numerous types of non-biological deposits that look similar to the kinds of fossils likely to be found if the planet ever supported life, a study says. Telling these false fossils apart from what could be evidence of ancient life on the surface of Mars -- which was temporarily habitable four billion years ago -- is key to the success of current and future missions. Astrobiologists from the Universities of Edinburgh and Oxford reviewed evidence of all known processes that could have created lifelike deposits in rocks on Mars. They identified dozens of processes -- with many more likely still undiscovered -- that can produce structures that mimic those of microscopic, simple lifeforms that may once have existed on Mars. Among the lifelike specimens these processes can create are deposits that look like bacterial cells and carbon-based molecules that closely resemble the building blocks of all known life. Because signs of life can be so closely mimicked by non-living processes, the origins of any fossil-like specimens found on Mars are likely to be very ambiguous, the team says. They call for greater interdisciplinary research to shed more light on how lifelike deposits could form on Mars, and thereby aid the search for evidence of ancient life there and elsewhere in the solar system.


PLANET ORBITING PAIR OF MASSIVE STARS
RAS

The European Southern Observatory’s Very Large Telescope (ESO’s VLT) has captured an image of a planet orbiting HIP 71865, a two-star system that can be seen with the naked eye. This is the hottest and most massive planet-hosting star system found to date, and the planet was spotted orbiting it at 100 times the distance Jupiter orbits the Sun. Some astronomers believed planets could not exist around stars this massive and this hot — until now. Located approximately 325 light-years away in the constellation Centaurus, the two-star system (also known as b Centauri) has at least six times the mass of the Sun, making it by far the most massive system around which a planet has been confirmed. Until now, no planets had been spotted around a star more than three times as massive as the Sun. Most massive stars are also very hot, and this system is no exception: its main star is a so-called B-type star that is over three times as hot as the Sun. Owing to its intense temperature, it emits large amounts of ultraviolet and X-ray radiation. The large mass and the heat from this type of star have a strong impact on the surrounding gas, that should work against planet formation. In particular, the hotter a star is, the more high-energy radiation it produces, which causes the surrounding material to evaporate faster. B-type stars are generally considered as quite destructive and dangerous environments, so it was believed that it should be exceedingly difficult to form large planets around them. But the new discovery shows planets can in fact form in such severe star systems. Indeed, the planet discovered, named b Centauri (AB)b or b Centauri b, is also extreme. It is 10 times as massive as Jupiter, making it one of the most massive planets ever found. Moreover, it moves around the star system in one of the widest orbits yet discovered, at a distance a staggering 100 times greater than the distance of Jupiter from the Sun. This large distance from the central pair of stars could be key to the planet’s survival.


STELLAR COCOON WITH ORGANIC MOLECULES AT EDGE OF OUR GALAXY
Niigata University

For the first time, astronomers have detected a newborn star and the surrounding cocoon of complex organic molecules at the edge of our Galaxy, which is known as the extreme outer Galaxy. The scientists from Niigata University (Japan), Academia Sinica Institute of Astronomy and Astrophysics (Taiwan), and the National Astronomical Observatory of Japan, used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to observe a newborn star (protostar) in the WB89-789 region, located in the extreme outer Galaxy. A variety of carbon-, oxygen-, nitrogen-, sulphur-, and silicon-bearing molecules, including complex organic molecules containing up to nine atoms, were detected. Such a protostar, as well as the associated cocoon of chemically-rich molecular gas, were for the first time detected at the edge of our Galaxy. The ALMA observations reveal that various kinds of complex organic molecules, such as methanol (CH3OH), ethanol (C2H5OH), methyl formate (HCOOCH3), dimethyl ether (CH3OCH3), formamide (NH2CHO), propanenitrile (C2H5CN), etc., are present even in the primordial environment of the extreme outer Galaxy. Such complex organic molecules potentially act as the feedstock for larger prebiotic molecules. Interestingly, the relative abundances of complex organic molecules in this newly discovered object resemble remarkably well what is found in similar objects in the inner Galaxy. The observations suggest that complex organic molecules are formed with similar efficiency even at the edge of our Galaxy, where the environment is very different from the solar neighborhood.

It is believed that the outer part of our Galaxy still harbours a primordial environment that existed in the early epoch of galaxy formation. The environmental characteristics of the extreme outer Galaxy, e.g., low abundance of heavy elements, small or no perturbation from Galactic spiral arms, are very different from those seen in the present-day solar neighborhood. Because of its unique characteristics, the extreme outer Galaxy is an excellent laboratory to study star formation and the interstellar medium in the past Galactic environment. It is not yet clear, however, if such a chemical complexity is common in the outer part of the Galaxy. Complex organic molecules are of special interest, because some of them are connected to prebiotic molecules formed in space. The team is planning to observe a larger number of star-forming regions in the future, and hopes to clarify whether chemically-rich systems, as seen in our Solar System, are ubiquitous through the history of the Universe.


FIFTH OF GALAXIES IN EARLY UNIVERSE STILL HIDDEN
University of Copenhagen - Faculty of Science

Astronomers have discovered two previously invisible galaxies billions of light-years away. Their discovery suggests that up to one in five such distant galaxies remain hidden from our telescopes, camouflaged by cosmic dust. The new knowledge changes perceptions of our Universe's evolution since the Big Bang. The new discovery suggests that the very early Universe contains many more galaxies than previously assumed. They simply lie hidden behind dust consisting of small particles from stars. However, they can now be detected thanks to the ALMA telescope and the method used by the researchers. To help with that task, NASA, ESA and the Canadian Space Agency have built a new super telescope, the James Webb Space Telescope, which is expected to be launched into orbit on the 18th of December 2021. With its strength and improved technology, the telescope will gaze even deeper into the Universe and contribute new knowledge about its origins. This will, among many other things, help Cosmic Dawn researchers at the Niels Bohr Institute see through the cosmic dust. Astronomers are trying to put the big puzzle about the Universe's formation together and answer the most basic question: 'Where does it all come from?' The invisible galaxies that have been discovered in the early Universe are some of the first building blocks of the mature galaxies we see around us in the Universe today. So that's where it all began.
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DARK-MATTER FREE GALAXIES
Royal Astronomical Society

An international team of astronomers has found no trace of dark matter in the galaxy AGC 114905, despite taking detailed measurements over a course of forty hours with state-of-the-art telescopes. The galaxy in question, AGC 114905, is about 250 million light-years away. It is classified as an ultra-diffuse dwarf galaxy, with the name 'dwarf galaxy' referring to its luminosity and not to its size. The galaxy is about the size of our own Milky Way but contains a thousand times fewer stars. The prevailing idea is that all galaxies, and certainly ultra-diffuse dwarf galaxies, can only exist if they are held together by dark matter. the researchers collected data on the rotation of gas in AGC 114905 for 40 hours between July and October 2020 using the VLA telescope. Subsequently, they made a graph showing the distance of the gas from the centre of the galaxy on the x-axis and the rotation speed of the gas on the y-axis. This is a standard way to reveal the presence of dark matter. The graph shows that the motions of the gas in AGC 114905 can be completely explained by just normal matter. In their scientific publication, the researchers list the possible explanations for the lack of dark matter one by one. For example, AGC 114905 could have been stripped of dark matter by large nearby galaxies. But there are none. And in the most reputed galaxy formation framework, the so called cold dark matter model would have to introduce extreme parameter values that are far beyond the usual range. Also with modified Newtonian dynamics, an alternative theory to cold dark matter, we cannot reproduce the motions of the gas within the galaxy. According to the researchers, there is one more assumption that could change their conclusions. That is the estimated angle at which they think they are observing the galaxy. But that angle has to deviate very much from the estimate before there is room for dark matter again. Meanwhile, the researchers are examining a second ultra-diffuse dwarf galaxy in detail. If again observe no trace of dark matter in that galaxy, it will make the case for dark matter poor galaxies even stronger.