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Author Topic: Mid June Astronomy Bulletin  (Read 211 times)

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Mid June Astronomy Bulletin
« on: June 12, 2022, 12:02 »
Lund University
The emergence of a mysterious area in the South Atlantic where the geomagnetic field strength is decreasing rapidly, has led to speculation that Earth is heading towards a magnetic polarity reversal. However, a new study that pieces together evidence stretching back 9,000 years, suggests that the current changes aren't unique, and that a reversal may not be in the cards after all. The Earth's magnetic field acts as an invisible shield against the life-threatening environment in space, and solar winds that would otherwise sweep away the atmosphere. However, the magnetic field is not stable, and at irregular intervals at an average of every 200,000 years polarity reversals happen. This means that the magnetic North and South poles swap places.  During the past 180 years, Earth's magnetic field strength has decreased by about 10 percent. Simultaneously, an area with an unusually weak magnetic field has grown in the South Atlantic off the coast of South America. This area, where satellites have malfunctioned several times due to exposure to highly charged particles from the sun, is called the South Atlantic Anomaly. These developments have led to speculation that we may be heading for a polarity reversal. However, the new study suggests this may not be the case.  The results are based on analyses of burnt archaeological artifacts, volcanic samples and sediment drill cores, all of which carry information about the Earth's magnetic field. These include clay pots that have been heated up to over 580 degrees Celsius, volcanic lava that has solidified, and sediments that have been deposited in lakes or in the sea. The objects act as time capsules, and carry information about the magnetic field in the past. Using sensitive instruments, the researchers have been able to measure these magnetizations and recreate the direction and strength of the magnetic field at specific places and times.  By studying how the magnetic field has changed, researchers can learn more about the underlying processes in the Earth's core that generate the field. The new model can also be used to date both archaeological and geological records, by comparing measured and modelled variations in the magnetic field. And reassuringly, it has led them to a conclusion regarding speculations about an imminent polarity reversal:


China has successfully launched another manned mission to its new space station, sending three astronauts who will continue construction work for six months, The team will live and work at the Tiangong Space Station's Tianhe core module for six months before returning to Earth in December. Tiangong means Heavenly Palace.  This is the third crewed mission during the construction of the space station, which China plans to have fully crewed and operational by December 2022. The first crewed mission, a three-month stay by three other astronauts, was completed in September 2021. The second, Shenzhou-13, saw three astronauts spend six months in space for the first time.  Six months is the standard mission duration for many countries -- but it is an important opportunity for Chinese astronauts to become accustomed to a long-term stay in space and help prepare future astronauts to do the same.  Six space missions have been scheduled before the end of the year, including another crewed mission, two laboratory modules and two cargo missions.   The modules will be assembled into a T-shaped structure, along with the Tianhe core cabin -- the main living space for the astronauts -- which will be expanded from 50 cubic metres to 110 cubic metres.  At the end of the Shenzhou-14 mission, another three astronauts are expected to rotate and live with the crew for five to 10 days, bringing the number of Chinese astronauts in space at the same time to a record six.

Once construction is completed, the Tiangong space station is expected to last for 15 years. China plans to launch two crewed missions and two cargo missions to the station every year   The Shenzhou-13 mission last year was a major step for the country's young space program, which is rapidly becoming one of the world's most advanced.  China's space program was late to the game, only established in the early 1970s, years after American astronaut Neil Armstrong had already landed on the Moon. But the chaos of China's Cultural Revolution stopped the nation's space effort in its tracks -- and progress was postponed until the early 1990s.  The government has since invested billions of dollars into the space program -- and the payoff has been evident. China successfully landed an exploratory rover on the Moon in December 2020 and one on Mars in May 2021. The first module of the Tiangong Space Station launched in April 2021.  China's ambitions span years into the future, with grand plans for space exploration, research and commercialization. One of the biggest ventures will be building a joint China-Russia research station on the Moon's south pole by 2035 -- a facility that will be open to international participation.


The Venus Cloud Discontinuity is a relatively new discovery, photographed by Japan's Venus orbiter Akatsuki in 2016 and first spotted by JAXA scientist Javier Peralta. The massive structure cuts vertically across Venus's equator, stretching almost 5000 miles from end to end, and circles the planet faster than 200 mph, making one lap every ~5 Earth days.  Researchers following up on the discovery soon stumbled onto another surprise. Older photographs of Venus showed it, too.  The Cloud Discontinuity] is a recurrent phenomenon that has gone unnoticed since at least the year 1983. How do you overlook something so big? Visually, the Cloud Discontinuity is hidden underneath Venus's opaque cloudtops. To see it, you have to use an infrared filter, which reveals heat trickling up from below. Indeed, this is how amateurs are tracking the disturbance:  Researchers still aren't sure what the Cloud Discontinuity is.   Whatever it is, the structure might help solve a longstanding mystery: Why does Venus's atmosphere rotate so much faster than the planet itself? The hot, deadly air on Venus spins nearly 60 times faster than its surface, an effect known as "super-rotation." Venus's Cloud Discontinuity could be assisting the spin-up by transporting angular momentum from the deep atmosphere to the cloudtops.

Universiteit van Amsterdam
Clouds of ultralight particles can form around rotating black holes. A team of physicists now show that these clouds would leave a characteristic imprint on the gravitational waves emitted by binary black holes.  Black holes are generally thought to swallow all forms of matter and energy surrounding them. It has long been known, however, that they can also shed some of their mass through a process called superradiance. While this phenomenon is known to occur, it is only effective if new, so far unobserved particles with very low mass exist in nature, as predicted by several theories beyond the Standard Model of particle physics.  When mass is extracted from a black hole via superradiance, it forms a large cloud around the black hole, creating a so-called gravitational atom. Despite the immensely larger size of a gravitational atom, the comparison with sub-microscopic atoms is accurate because of the similarity of the black hole plus its cloud with the familiar structure of ordinary atoms, where clouds of electrons surround a core of protons and neutrons.  In the new work, the researchers studied the gravitational equivalent of the so-called 'photoelectric effect'. In this well-known process, which for example is exploited in solar cells to produce an electric current, ordinary electrons absorb the energy of incident particles of light and are thereby ejected from a material -- the atoms 'ionize'. In the gravitational analogue, when the gravitational atom is part of a binary system of two heavy objects, it gets perturbed by the presence of the massive companion, which could be a second black hole or a neutron star. Just as the electrons in the photoelectric effect absorb the energy of the incident light, the cloud of ultralight particles can absorb the orbital energy of the companion, so that some of the cloud gets ejected from the gravitational atom.  The team demonstrated that this process may dramatically alter the evolution of such binary systems, significantly reducing the time required for the components to merge with each other. Moreover, the ionization of the gravitational atom is enhanced at very specific distances between the binary black holes, which leads to sharp features in the gravitational waves that we detect from such mergers. Future gravitational wave interferometers -- machines similar to the LIGO and Virgo detectors that over the past few years have shown us the first gravitational waves from black holes -- could observe these effects. Finding the predicted features from gravitational atoms would provide distinctive evidence for the existence of new ultralight particles.

Kavli Institute for the Physics and Mathematics of the Universe
For the first time, researchers have created simulations that directly recreate the full life cycle of some of the largest collections of galaxies observed in the distant Universe 11 billion years ago.  Cosmological simulations are crucial to studying how the Universe became the shape it is today, but many do not typically match what astronomers observe through telescopes. Most are designed to match the real Universe only in a statistical sense. Constrained cosmological simulations, on the other hand, are designed to directly reproduce the structures we actually observe in the universe. However, most existing simulations of this kind have been applied to our local Universe, meaning close to Earth, but never for observations of the distant Universe. A team of researchers, were interested in distant structures like massive galaxy protoclusters, which are ancestors of present-day galaxy clusters before they could clump under their own gravity. They found current studies of distant protoclusters were sometimes oversimplified, meaning they were done with simple models and not simulations.  Their result was COSTCO (COnstrained Simulations of The COsmos Field).  Developing the simulation was much like building a time machine. Because light from the distant Universe is only reaching Earth now, the galaxies telescopes observe today are a snapshot of the past.  In this sense, the researchers took snapshots of "young" grandparent galaxies in the Universe and then fast forwarded their age to study how clusters of galaxies would form.  The light from galaxies the researchers used travelled a distance of 11 billion light-years to reach us.
Another important reason why the researchers created these simulations was to test the standard model of cosmology, that is used to describe the physics of the Universe. By predicting the final mass and final distribution of structures in a given space, researchers could unveil previously undetected discrepancies in our current understanding of the Universe.  Using their simulations, the researchers were able to find evidence of three already published galaxy protoclusters and disfavor one structure. On top of that, they were able to identify five more structures that consistently formed in their simulations. This includes the Hyperion proto-supercluster, the largest and earliest proto-supercluster known today that is 5000 times the mass of our Milky Way galaxy, which the researchers found out it will collapse into a large 300 million light year filament.  Their work is already being applied to other projects including those to study the cosmological environment of galaxies, and absorption lines of distant quasars to name a few.


Russian space agency Roscosmos says it will restart a telescope shut down by Germany over Moscow's invasion of Ukraine. But a noted expert has warned that this might be dangerous to the instrument.  The X-ray telescope, named eROSITA, works in tandem with a Russian instrument, the ART-XC, to scan distant galaxies in what was a joint German-Russian mission until Germany put its cooperation on ice over Russia's invasion.  The telescope was launched into space from the Baikonur launch site in July 2019.  However, the scientific director of the Spekr-RG project said that attempts to restart the telescope without German cooperation could be detrimental to the device itself.  The recommissioning could take place only with Germany's consent; otherwise, the telescope would be in danger of breaking down.   The Spektr-RG mission on which it is deployed along with the Russian telescope aims, among other things, to detect black holes.  Until eROSITA was put into sleep mode on February 26, two days after Russia started its invasion,  Russian and German researchers had been able to jointly evaluate the data sent by the two devices.   At the time it was shut down, eROSITA had completed four of its planned eight full-sky surveys. Data from the first four are still being evaluated by scientists.

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