Researchers advance detection of gravitational waves to study collisions of neutron stars and black holes

Researchers at the University of Minnesota Twin Cities College of Science and Engineering co-led a new study by an international team that will improve the detection of gravitational waves -- ripples in space and time.

The research aims to send alerts to astronomers and astrophysicists within 30 seconds after the detection, helping to improve the understanding of neutron stars and black holes and how heavy elements, including gold and uranium, are produced.

The findings were recently published in the Proceedings of the National Academy of Sciences (PNAS).

Gravitational waves interact with spacetime by compressing it in one direction while stretching it in the perpendicular direction. That is why current state-of-the-art gravitational wave detectors are L-shaped and measure the relative lengths of the laser using interferometry, a measurement method which looks at the interference patterns produced by the combination of two light sources. Detecting gravitational waves requires measuring the length of the laser to precise measurements: equivalent to measuring the distance to the nearest star, around four light years away, down to the width of a human hair.

This research is part of the LIGO-Virgo-KAGRA (LVK) Collaboration, a network of gravitational wave interferometers across the world.

In the latest simulation campaign, data was used from previous observation periods and simulated gravitational wave signals were added to show the performance of the software and equipment upgrades. The software can detect the shape of signals, track how the signal behaves, and estimate what masses are included in the event, like neutron stars or black holes. Neutron stars are the smallest, most dense stars known to exist and are formed when massive stars explode in supernovas.

Once this software detects a gravitational wave signal, it sends out alerts to subscribers, which usually include astronomers or astrophysicists, to communicate where the signal was located in the sky. With the upgrades in this observing period, scientists are able to send alerts faster, under 30 seconds, after the detection of a gravitational wave.

"With this software, we can detect the gravitational wave from neutron star collisions that is normally too faint to see unless we know exactly where to look," said Andrew Toivonen, a Ph.D. student in the University of Minnesota Twin Cities School of Physics and Astronomy. "Detecting the gravitational waves first will help locate the collision and help astronomers and astrophysicists to complete further research."

Astronomers and astrophysicists could use this information to understand how neutron stars behave, study nuclear reactions between neutron stars and black holes colliding, and how heavy elements, including gold and uranium, are produced.

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Ancient stars made extraordinarily heavy elements

How heavy can an element be? An international team of researchers has found that ancient stars were capable of producing elements with atomic masses greater than 260, heavier than any element on the periodic table found naturally on Earth. The finding deepens our understanding of element formation in stars.

We are, literally, made of star stuff. Stars are element factories, where elements constantly fuse or break apart to create other lighter or heavier elements.

When we refer to light or heavy elements, we're talking about their atomic mass.

Broadly speaking, atomic mass is based on the number of protons and neutrons in the nucleus of one atom of that element.

The heaviest elements are only known to be created in neutron stars via the rapid neutron capture process, or r-process.

Picture a single atomic nucleus floating in a soup of neutrons.

Suddenly, a bunch of those neutrons get stuck to the nucleus in a very short time period -- usually in less than one second -- then undergo some internal neutron-to-proton changes, and voila!

A heavy element, such as gold, platinum or uranium, forms.

The heaviest elements are unstable or radioactive, meaning they decay over time.

One way that they do this is by splitting, a process called fission.

"The r-process is necessary if you want to make elements that are heavier than, say, lead and bismuth," says Ian Roederer, associate professor of physics at North Carolina State University and lead author of the research.

Roederer was previously at the University of Michigan.

"You have to add many neutrons very quickly, but the catch is that you need a lot of energy and a lot of neutrons to do so," Roederer says.

"We have a general idea of how the r-process works, but the conditions of the process are quite extreme," Roederer says.

"We don't have a good sense of how many different kinds of sites in the universe can generate the r-process, we don't know how the r-process ends, and we can't answer questions like, how many neutrons can you add? Or, how heavy can an element be? So we decided to look at elements that could be made by fission in some well-studied old stars to see if we could start to answer some of these questions."

The team took a fresh look at the amounts of heavy elements in 42 well-studied stars in the Milky Way.

The stars were known to have heavy elements formed by the r-process in earlier generations of stars.

By taking a broader view of the amounts of each heavy element found in these stars collectively, rather than individually as is more common, they identified previously unrecognized patterns.

Those patterns signaled that some elements listed near the middle of the periodic table -- such as silver and rhodium -- were likely the remnants of heavy element fission.

The team was able to determine that the r-process can produce atoms with an atomic mass of at least 260 before they fission.

"That 260 is interesting because we haven't previously detected anything that heavy in space or naturally on Earth, even in nuclear weapon tests," Roederer says.

"But seeing them in space gives us guidance for how to think about models and fission -- and could give us insight into how the rich diversity of elements came to be."

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Massive space explosion observed creating elements needed for life

Scientists have observed the creation of rare chemical elements in the second-brightest gamma-ray burst ever seen -- casting new light on how heavy elements are made.

Researchers examined the exceptionally bright gamma-ray burst GRB 230307A, which was caused by a neutron star merger. The explosion was observed using an array of ground and space-based telescopes, including NASA's James Webb Space Telescope, Fermi Gamma-ray Space Telescope, and Neil Gehrels Swift Observatory.

Publishing their findings today in Nature (25 Oct), the international research team which included experts from the University of Birmingham, reveal that they found the heavy chemical element tellurium, in the aftermath of the explosion.

Other elements such as iodine and thorium, which are needed to sustain life on earth, are also likely to be amongst the material ejected by the explosion, also known as a kilonova.

Dr Ben Gompertz, Assistant Professor of Astronomy at the University of Birmingham, and co-author of the study explains: "Gamma-ray bursts come from powerful jets travelling at almost the speed of light -- in this case driven by a collision between two neutron stars. These stars spent several billion years spiralling towards one another before colliding to produce the gamma-ray burst we observed in March this year. The merger site is the approximate length of the Milky Way (about 120,000 light-years) outside of their home galaxy, meaning they must have been launched out together.

"Colliding neutron stars provide the conditions needed to synthesise very heavy elements, and the radioactive glow of these new elements powered the kilonova we detected as the blast faded. Kilonovae are extremely rare and very difficult to observe and study, which is why this discovery is so exciting."

GRB 230307A was one of the brightest gamma-ray bursts ever observed -- over a million times brighter than the entire Milky Way Galaxy combined. This is the second time individual heavy elements have been detected using spectroscopic observations after a neutron star merger, providing invaluable insight into how these vital building blocks needed for life are formed.

Lead author of the study Andrew Levan, Professor of Astrophysics at Radboud University in the Netherlands, said: "Just over 150 years since Dmitri Mendeleev wrote down the periodic table of elements, we are now finally in the position to start filling in those last blanks of understanding where everything was made, thanks to the James Webb Telescope."

GRB 230307A lasted for 200 seconds, meaning it is categorised as a long-duration gamma-ray burst. This is unusual as short gamma-ray bursts, which last less than two seconds, are more commonly caused by neutron star mergers. Long gamma-ray bursts like this one are usually caused by the explosive death of a massive star.

The researchers are now seeking to learn more about how these neutron star mergers work and how they power these huge element-generating explosions.

Dr Samantha Oates, a co-author of the study while a postdoctoral research fellow at the University of Birmingham (now a lecturer at Lancaster University) said: "Just a few short years ago discoveries like this one would not have been possible, but thanks to the James Webb Space Telescope we can observe these mergers in exquisite detail."

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Astronomers discover newborn galaxies with the James Webb Space Telescope

With the launch of the James Webb Space Telescope, astronomers are now able to peer so far back in time that we are approaching the epoch where we think that the first galaxies were created. Throughout most of the history of the Universe, galaxies seemingly tend to follow a tight relation between how many stars they have formed, and how many heavy elements they have formed. But for the first time we now see signs that this relation between the amount of stars and elements does not hold for the earliest galaxies. The reason is likely that these galaxies simply are in the process of being created, and have not yet had the time to create the heavy elements.

The Universe is teeming with galaxies -- immense collections of stars and gas -- and as we peer deep into the cosmos, we see them near and far. Because the light has spent more time reaching us, the farther away a galaxy is, we are essentially looking back through time, allowing us to construct a visual narrative of their evolution throughout the history of the Universe.

Observations have shown us that galaxies through the last 12 billion years -- that is, 5/6 of the age of the Universe -- have been living their life in a form of equilibrium: There appears to be a fundamental, tight relation between on one hand how many stars they have formed, and on the other hand how many heavy elements they have formed. In this context, "heavy elements," means everything heavier than hydrogen and helium.

This relation makes sense, because the Universe consisted originally only of these two lightest elements. All heavier elements, such as carbon, oxygen, and iron, was created later by the stars.

James Webb peers deeper

The very first galaxies should therefore be "unpolluted" by heavy elements. But until recently we haven't been able to look so far back in time. In addition to being far away, the reason is that the longer light travels through space, the redder it becomes. For the most distant galaxies you have to look all the way into the infrared part of the spectrum, and only with the launch of James Webb did we have a telescope big and sensitive enough to see so far.

And the space telescope did not disappoint: Several has James Webb broken its own record for the most distant galaxy, and now it finally seems that we are reaching the epoch where some of the very first galaxies were created.

In a new study, published today in the scientific journal Nature Astronomy, af team of astronomers from the Danish research center Cosmic Dawn Center at the Niels Bohr Institute and DTU Space in Copenhagen, has discovered what seems indeed to be some of the very first galaxies which are still in the process of being formed.

"Until recently it has been near-impossible to study how the first galaxies are formed in the early Universe, since we simply haven't had the adequate instrumentation. This has now changed completely with the launch of James Webb," says Kasper Elm Heintz, leader of the study and assistant professor at the Cosmic Dawn Center.

Fundamental relation breaks down

The relationship between the total stellar mass of the galaxy and the amount of heavy elements is a bit more complex than that. How fast the galaxy produces new stars also has something to say. But if you correct for that, you get a beautiful, linear relationship: The more massive the galaxy, the more heavy elements.

But this relation is now being challenged by the latest observations.

"When we analyzed the light from 16 of these first galaxies, we saw that they had significantly less heavy elements, compared to what you'd expect from their stellar masses and the amount of new stars they produced," says Kasper Elm Heintz.

In fact the galaxies turned out to have, on average, four times less amounts of heavy elements that in the later Universe. These results are in stark contrast to the current model where galaxies evolve in a form of equilibrium throughout most of the history of the Universe.

Predicted by theories

The result is not entirely surprising though. Theoretical models of galaxy formation, based on detailed computer programs, do predict something similar. But now we've seen it!

The explanation, as proposed by the autors in the article, is simply that we are witnessing galaxies in the process of being created. Gravity has gathered the first clumps of gas, which have begun to form stars.

If the galaxies then lived their lives undisturbed, the stars would quickly enrich them with heavy elements. But in between the galaxies at that time were large amounts of fresh, unpolluted gas, streaming down to the galaxies faster than the stars can keep up.

"The result gives us the first insight into the earliest stages of galaxy formation which appear to be more intimately connected with the gas in between the galaxies than we thought.

This is one of the first James Webb observations on this topic, so we're still waiting to see what the larger, more comprehensive observations that are currently being carried out can tell us.

Read more at Science Daily

New exoplanet discovery builds better understanding of planet formation

An international team of scientists have discovered an unusual Jupiter-sized planet orbiting a low-mass star called TOI-4860, located in the Corvus constellation.

The newly discovered gas giant, named TOI-4860 b, is an unusual planet for two reasons: stars of such low mass are not expected to host planets like Jupiter, and the planet appears to be particularly enriched by heavy elements.

The study, led by University of Birmingham astronomers, is published today (Friday 4th August) in a letter published within the Monthly Notices of the Royal Astronomical Society.

The planet was initially identified using NASA's Transiting Exoplanet Survey Satellite as a drop of brightness while transiting in front of its host star, but that data alone was insufficient to confirm that it was a planet.

The team used the SPECULOOS South Observatory, located in the Atacama Desert in Chile, to measure the planetary signal in several wavelengths and validated the planetary nature. The astronomers also observed the planet just before and after it disappeared behind its host star, noticing that there was no change in light, meaning the planet was not emitting any. Finally, the team collaborated with a Japanese group using the Subaru Telescope in Hawai'i. Together they measured the mass of the planet to fully confirm it.

Following this star and confirming its planet was the initiative of a group of PhD students within the SPECULOOS project.

George Dransfield, one of those PhD students, who recently submitted her thesis at the University of Birmingham, explains: "Under the canonical planet formation model, the less mass a star has, the less massive is the disc of material around that star.

"Since planets are created from that disc, high-mass planets like Jupiter, were widely expected not to form. However, we were curious about this and wanted to check planetary candidates to see if it was possible. TOI-4860 is our first confirmation and also the lowest mass star hosting such a high mass planet."

Amaury Triaud, Professor of Exoplanetology at the University of Birmingham, who led the study said: "I am ever thankful to the bright PhD students of our team for proposing to observe systems like TOI-4860. Their work has really paid off since planets like TOI-4860 are vital to deepening our understanding of planet formation.

"A hint of what might have happened is hidden in the planetary properties, which appear particularly enriched in heavy elements. We have detected something similar in the host star too, so it is likely that an abundance of heavy elements catalysed the planet formation process."

The new gas giant takes about 1.52 days to complete a full orbit around its host star, but because its host is a cold low mass star, the planet itself can be referred to as a 'Warm Jupiter'. This is a subclass of planet that holds particular interest for astronomers looking to build on their initial observations and learn more about how these kinds of planets are formed.

Mathilde Timmermans, another student of the SPECULOOS project, working at the University of Liege in Belgium concludes: "Thanks to its very short orbital period, and to the properties of its host star, the discovery of TOI-4860 b provides a brilliant opportunity to study the atmospheric properties of a warm Jupiter and learn more about how gas giants are formed."

Read more at Science Daily

Heaviest element yet detected in an exoplanet atmosphere

Using the European Southern Observatory's Very Large Telescope (ESO's VLT), astronomers have discovered the heaviest element ever found in an exoplanet atmosphere -- barium. They were surprised to discover barium at high altitudes in the atmospheres of the ultra-hot gas giants WASP-76 b and WASP-121 b -- two exoplanets, planets which orbit stars outside our Solar System. This unexpected discovery raises questions about what these exotic atmospheres may be like.

"The puzzling and counterintuitive part is: why is there such a heavy element in the upper layers of the atmosphere of these planets?" says Tomás Azevedo Silva, a PhD student at the University of Porto and the Instituto de Astrofísica e Ciências do Espaço (IA) in Portugal who led the study published today in Astronomy & Astrophysics.

WASP-76 b and WASP-121 b are no ordinary exoplanets. Both are known as ultra-hot Jupiters as they are comparable in size to Jupiter whilst having extremely high surface temperatures soaring above 1000°C. This is due to their close proximity to their host stars, which also means an orbit around each star takes only one to two days. This gives these planets rather exotic features; in WASP-76 b, for example, astronomers suspect it rains iron.

But even so, the scientists were surprised to find barium, which is 2.5 times heavier than iron, in the upper atmospheres of WASP-76 b and WASP-121 b. "Given the high gravity of the planets, we would expect heavy elements like barium to quickly fall into the lower layers of the atmosphere," explains co-author Olivier Demangeon, a researcher also from the University of Porto and IA.

"This was in a way an 'accidental' discovery," says Azevedo Silva. "We were not expecting or looking for barium in particular and had to cross-check that this was actually coming from the planet since it had never been seen in any exoplanet before."

The fact that barium was detected in the atmospheres of both of these ultra-hot Jupiters suggests that this category of planets might be even stranger than previously thought. Although we do occasionally see barium in our own skies, as the brilliant green colour in fireworks, the question for scientists is what natural process could cause this heavy element to be at such high altitudes in these exoplanets. "At the moment, we are not sure what the mechanisms are," explains Demangeon.

In the study of exoplanet atmospheres ultra-hot Jupiters are extremely useful. As Demangeon explains: "Being gaseous and hot, their atmospheres are very extended and are thus easier to observe and study than those of smaller or cooler planets."

Determining the composition of an exoplanet's atmosphere requires very specialised equipment. The team used the ESPRESSO instrument on ESO's VLT in Chile to analyse starlight that had been filtered through the atmospheres of WASP-76 b and WASP-121 b. This made it possible to clearly detect several elements in them, including barium.

Read more at Science Daily

Pushing the boundaries of chemistry: Properties of heaviest element studied so far measured at GSI/FAIR

An international research team has succeeded in gaining new insights into the chemical properties of the superheavy element flerovium -- element 114 -- at the accelerator facilities of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt. The measurements show that flerovium is the most volatile metal in the periodic table. Flerovium is thus the heaviest element in the periodic table that has been chemically studied. With the results, published in the journal Frontiers in Chemistry, GSI confirms its leading position in the study of the chemistry of superheavy elements and opens new perspectives for the international facility FAIR (Facility for Antiproton and Ion Research), which is currently under construction.

Under the leadership of groups from Darmstadt and Mainz, the two longest-lived flerovium isotopes currently known, flerovium-288 and flerovium-289, were produced using the accelerator facilities at GSI/FAIR and were chemically investigated at the TASCA experimental setup. In the periodic table, flerovium is placed below the heavy metal lead. However, early predictions had postulated that relativistic effects of the high charge in the nucleus of the superheavy element on its valence electrons would lead to noble gas-like behavior, while more recent ones had rather suggested a weakly metallic behavior. Two previously conducted chemistry experiments, one of them at GSI in Darmstadt in 2009, led to contradictory interpretations. While the three atoms observed in the first experiment were used to infer noble gas-like behavior, the data obtained at GSI indicated metallic character based on two atoms. The two experiments were unable to clearly establish the character. The new results show that, as expected, flerovium is inert but capable of forming stronger chemical bonds than noble gases, if conditions are suitable. Flerovium is consequently the most volatile metal in the periodic table.

Flerovium is thus the heaviest chemical element whose character has been studied experimentally. With the determination of the chemical properties, GSI/FAIR confirm their leading position in the research of superheavy elements. "Exploring the boundaries of the periodic table has been a pillar of the research program at GSI since the beginning and will be so at FAIR in the future. The fact that a few atoms can already be used to explore the first fundamental chemical properties, giving an indication of how larger quantities of these substances would behave, is fascinating and possible thanks to the powerful accelerator facility and the expertise of the worldwide collaboration," elaborates Professor Paolo Giubellino, Scientific Managing Director of GSI and FAIR. "With FAIR, we are bringing the universe into the laboratory and explore the limits of matter, also of the chemical elements."

Six weeks of experimentation

The experiments conducted at GSI/FAIR to clarify the chemical nature of flerovium lasted a total of six weeks. For this purpose, four trillion calcium-48 ions were accelerated to ten percent of the speed of light every second by the GSI linear accelerator UNILAC and fired at a target containing plutonium-244, resulting in the formation of a few flerovium atoms per day.

The formed flerovium atoms recoiled from the target into the gas-filled separator TASCA. In its magnetic field, the formed isotopes, flerovium-288 and flerovium-289, which have lifetimes on the order of a second, were separated from the intense calcium ion beam and from byproducts of the nuclear reaction. They penetrated a thin film, thus entering the chemistry apparatus, where they were stopped in a helium/argon gas mixture. This gas mixture flushed the atoms into the COMPACT gas chromatography apparatus, where they first came into contact with silicon oxide surfaces. If the bond to silicon oxide was too weak, the atoms were transported further, over gold surfaces -- first those kept at room temperature, and then over increasingly colder ones, down to about -160 °C. The surfaces were deposited as a thin coating on special nuclear radiation detectors, which registered individual atoms by spatially resolved detection of the radioactive decay. Since the decay products undergo further radioactive decay after a short lifetime, each atom leaves a characteristic signature of several events from which the presence of a flerovium atom can unambiguously be inferred.

One atom per week for chemistry

"Thanks to the combination of the TASCA separator, the chemical separation and the detection of the radioactive decays, as well as the technical development of the gas chromatography apparatus since the first experiment, we have succeeded in increasing the efficiency and reducing the time required for the chemical separation to such an extent that we were able to observe one flerovium atom every week," explains Dr. Alexander Yakushev of GSI/FAIR, the spokesperson for the international experiment collaboration.

Six such decay chains were found in the data analysis. Since the setup is similar to that of the first GSI experiment, the newly obtained data could be combined with the two atoms observed at that time and analyzed together. None of the decay chains appeared within the range of the silicon oxide-coated detector, indicating that flerovium does not form a substantial bond with silicon oxide. Instead, all were transported with the gas into the gold-coated portion of the apparatus within less than a tenth of a second. The eight events formed two zones: a first in the region of the gold surface at room temperature, and a second in the later part of the chromatograph, at temperatures so low that a very thin layer of ice covered the gold, so that adsorption occurred on ice.

From experiments with lead, mercury and radon atoms, which served as representatives of heavy metals, weakly reactive metals as well as noble gases, it was known that lead forms a strong bond with silicon oxide, while mercury reaches the gold detector. Radon even flies over the first part of the gold detector at room temperature and is only partially retained at the lowest temperatures. Flerovium results could be compared with this behavior.

Apparently, two types of interaction of a flerovium species with the gold surface were observed. The deposition on gold at room temperature indicates the formation of a relatively strong chemical bond, which does not occur in noble gases. On the other hand, some of the atoms appear never to have had the opportunity to form such bonds and have been transported over long distances of the gold surface, down to the lowest temperatures. This detector range represents a trap for all elemental species. This complicated behavior can be explained by the morphology of the gold surface: it consists of small gold clusters, at the boundaries of which very reactive sites occur, apparently allowing the flerovium to bond. The fact that some of the flerovium atoms were able to reach the cold region indicates that only the atoms that encountered such sites formed a bond, unlike mercury, which was retained on gold in any case. Thus, the chemical reactivity of flerovium is weaker than that of the volatile metal mercury. The current data cannot completely rule out the possibility that the first deposition zone on gold at room temperature is due to the formation of flerovium molecules. It also follows from this hypothesis, though, that flerovium is chemically more reactive than a noble gas element.

International and interdisciplinary collaboration as the key to understanding

The exotic plutonium target material for the production of the flerovium was provided in part by Lawrence Livermore National Laboratory (LLNL), USA. In the Department of Chemistry's TRIGA site at Johannes Gutenberg University Mainz (JGU), the material was electrolytically deposited onto thin titanium foils fabricated at GSI/FAIR. "There is not much of this material available in the world, and we are fortunate to have been able to use it for these experiments that would not otherwise be possible," said Dr. Dawn Shaughnessy, head of the Nuclear and Chemical Sciences Division at LLNL. "This international collaboration brings together skills and expertise from around the world to solve difficult scientific problems and answer long-standing questions, such as the chemical properties of flerovium."

"Our accelerator experiment was complemented by a detailed study of the detector surface in collaboration with several GSI departments as well as the Department of Chemistry and the Institute of Physics at JGU. This has proven to be key to understanding the chemical character of flerovium. As a result, the data from the two earlier experiments are now understandable and compatible with our new conclusions," says Christoph Düllmann, professor of nuclear chemistry at JGU and head of the research groups at GSI and at the Helmholtz Institute Mainz (HIM), a collaboration between GSI and JGU.

How the relativistic effects affect its neighbors, the elements nihonium (element 113) and moscovium (element 115), which have also only been officially recognized in recent years, is the subject of subsequent experiments. Initial data have already been obtained as part of the FAIR Phase 0 program at GSI. Furthermore, the researchers expect that significantly more stable isotopes of flerovium exist, but these have not yet been found. However, the researchers now already know that they can expect to find a metallic element.

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Gemini North spies ultra-faint fossil galaxy discovered on outskirts of Andromeda

An unusual ultra-faint dwarf galaxy has been discovered on the outer fringes of the Andromeda Galaxy thanks to the sharp eyes of 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.

An unusual ultra-faint dwarf galaxy has been discovered on the edge of the Andromeda Galaxy using several facilities of NSF's NOIRLab. The galaxy, called Pegasus V, was first detected as part of a systematic search for Andromeda dwarfs coordinated by David Martinez-Delgado from the Instituto de Astrofísica de Andalucía, Spain, when amateur astronomer Giuseppe Donatiello found an interesting 'smudge' in data in a DESI Legacy Imaging Surveys image. The image was taken with the US Department of Energy-fabricated Dark Energy Camera on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO). The data were processed through the Community Pipeline which is operated by NOIRLab's Community Science and Data Center (CSDC).

Follow-up deeper observations by astronomers using the larger, 8.1-meter Gemini North telescope with the GMOS instrument, revealed faint stars in Pegasus V, confirming that it is an ultra-faint dwarf galaxy on the outskirts of the Andromeda Galaxy. Gemini North in Hawai'i is one half of the International Gemini Observatory.

The observations with Gemini revealed that the galaxy appears to be extremely deficient in heavier elements compared to similar dwarf galaxies, meaning that it is very old and likely to be a fossil of the first galaxies in the Universe.

"We have found an extremely faint galaxy whose stars formed very early in the history of the Universe,"commented Michelle Collins, an astronomer at the University of Surrey, UK and lead author of the paper announcing this discovery. "This discovery marks the first time a galaxy this faint has been found around the Andromeda Galaxy using an astronomical survey that wasn't specifically designed for the task."

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 endeavor, 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 trouble with these extremely faint galaxies is that they have very few of the bright stars which we typically use to identify them and measure their distances," explained Emily Charles, a PhD student at the University of Surrey who was also involved in the study. "Gemini's 8.1-meter mirror allowed us to find faint, old stars which enabled us both to measure the distance to Pegasus V and to determine that its stellar population is extremely old."

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.

"We hope that further study of Pegasus V's chemical properties will provide clues into the earliest periods of star formation in the Universe," concluded Collins. "This little fossil galaxy from the early Universe may help us understand how galaxies form, and whether our understanding of dark matter is correct."

"The public-access Gemini North telescope provides an array of capabilities for community astronomers," said Martin Still, Gemini Program Officer at the National Science Foundation. "In this case, Gemini supported this international team to confirm the presence of the dwarf galaxy, associate it physically with the Andromeda Galaxy, and determine the metal-deficient nature of its evolved stellar population."

Read more at Science Daily

Where does gold come from? New insights into element synthesis in the universe

How are chemical elements produced in our Universe? Where do heavy elements like gold and uranium come from? Using computer simulations, a research team from the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, together with colleagues from Belgium and Japan, shows that the synthesis of heavy elements is typical for certain black holes with orbiting matter accumulations, so-called accretion disks. The predicted abundance of the formed elements provides insight into which heavy elements need to be studied in future laboratories -- such as the Facility for Antiproton and Ion Research (FAIR), which is currently under construction -- to unravel the origin of heavy elements. The results are published in the journal Monthly Notices of the Royal Astronomical Society.

All heavy elements on Earth today were formed under extreme conditions in astrophysical environments: inside stars, in stellar explosions, and during the collision of neutron stars. Researchers are intrigued with the question in which of these astrophysical events the appropriate conditions for the formation of the heaviest elements, such as gold or uranium, exist. The spectacular first observation of gravitational waves and electromagnetic radiation originating from a neutron star merger in 2017 suggested that many heavy elements can be produced and released in these cosmic collisions. However, the question remains open as to when and why the material is ejected and whether there may be other scenarios in which heavy elements can be produced.

Promising candidates for heavy element production are black holes orbited by an accretion disk of dense and hot matter. Such a system is formed both after the merger of two massive neutron stars and during a so-called collapsar, the collapse and subsequent explosion of a rotating star. The internal composition of such accretion disks has so far not been well understood, particularly with respect to the conditions under which an excess of neutrons forms. A high number of neutrons is a basic requirement for the synthesis of heavy elements, as it enables the rapid neutron-capture process or r-process. Nearly massless neutrinos play a key role in this process, as they enable conversion between protons and neutrons.

"In our study, we systematically investigated for the first time the conversion rates of neutrons and protons for a large number of disk configurations by means of elaborate computer simulations, and we found that the disks are very rich in neutrons as long as certain conditions are met," explains Dr. Oliver Just from the Relativistic Astrophysics group of GSI's research division Theory. "The decisive factor is the total mass of the disk. The more massive the disk, the more often neutrons are formed from protons through capture of electrons under emission of neutrinos, and are available for the synthesis of heavy elements by means of the r-process. However, if the mass of the disk is too high, the inverse reaction plays an increased role so that more neutrinos are recaptured by neutrons before they leave the disk. These neutrons are then converted back to protons, which hinders the r-process." As the study shows, the optimal disk mass for prolific production of heavy elements is about 0.01 to 0.1 solar masses. The result provides strong evidence that neutron star mergers producing accretion disks with these exact masses could be the point of origin for a large fraction of the heavy elements. However, whether and how frequently such accretion disks occur in collapsar systems is currently unclear.

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Neutron star collisions are 'goldmine' of heavy elements, study finds

Most elements lighter than iron are forged in the cores of stars. A star's white-hot center fuels the fusion of protons, squeezing them together to build progressively heavier elements. But beyond iron, scientists have puzzled over what could give rise to gold, platinum, and the rest of the universe's heavy elements, whose formation requires more energy than a star can muster.

A new study by researchers at MIT and the University of New Hampshire finds that of two long-suspected sources of heavy metals, one is more of a goldmine than the other.

The study, published today in Astrophysical Journal Letters, reports that in the last 2.5 billion years, more heavy metals were produced in binary neutron star mergers, or collisions between two neutron stars, than in mergers between a neutron star and a black hole.

The study is the first to compare the two merger types in terms of their heavy metal output, and suggests that binary neutron stars are a likely cosmic source for the gold, platinum, and other heavy metals we see today. The findings could also help scientists determine the rate at which heavy metals are produced across the universe.

"What we find exciting about our result is that to some level of confidence we can say binary neutron stars are probably more of a goldmine than neutron star-black hole mergers," says lead author Hsin-Yu Chen, a postdoc in MIT's Kavli Institute for Astrophysics and Space Research.

Chen's co-authors are Salvatore Vitale, assistant professor of physics at MIT, and Francois Foucart of UNH.

An efficient flash

As stars undergo nuclear fusion, they require energy to fuse protons to form heavier elements. Stars are efficient in churning out lighter elements, from hydrogen to iron. Fusing more than the 26 protons in iron, however, becomes energetically inefficient.

"If you want to go past iron and build heavier elements like gold and platinum, you need some other way to throw protons together," Vitale says.

Scientists have suspected supernovae might be an answer. When a massive star collapses in a supernova, the iron at its center could conceivably combine with lighter elements in the extreme fallout to generate heavier elements.

In 2017, however, a promising candidate was confirmed, in the form a binary neutron star merger, detected for the first time by LIGO and Virgo, the gravitational-wave observatories in the United States and in Italy, respectively. The detectors picked up gravitational waves, or ripples through space-time, that originated 130 million light years from Earth, from a collision between two neutron stars -- collapsed cores of massive stars, that are packed with neutrons and are among the densest objects in the universe.

The cosmic merger emitted a flash of light, which contained signatures of heavy metals.

"The magnitude of gold produced in the merger was equivalent to several times the mass of the Earth," Chen says. "That entirely changed the picture. The math showed that binary neutron stars were a more efficient way to create heavy elements, compared to supernovae."

A binary goldmine

Chen and her colleagues wondered: How might neutron star mergers compare to collisions between a neutron star and a black hole? This is another merger type that has been detected by LIGO and Virgo and could potentially be a heavy metal factory. Under certain conditions, scientists suspect, a black hole could disrupt a neutron star such that it would spark and spew heavy metals before the black hole completely swallowed the star.

The team set out to determine the amount of gold and other heavy metals each type of merger could typically produce. For their analysis, they focused on LIGO and Virgo's detections to date of two binary neutron star mergers and two neutron star -- black hole mergers.

The researchers first estimated the mass of each object in each merger, as well as the rotational speed of each black hole, reasoning that if a black hole is too massive or slow, it would swallow a neutron star before it had a chance to produce heavy elements. They also determined each neutron star's resistance to being disrupted. The more resistant a star, the less likely it is to churn out heavy elements. They also estimated how often one merger occurs compared to the other, based on observations by LIGO, Virgo, and other observatories.

Finally, the team used numerical simulations developed by Foucart, to calculate the average amount of gold and other heavy metals each merger would produce, given varying combinations of the objects' mass, rotation, degree of disruption, and rate of occurrence.

On average, the researchers found that binary neutron star mergers could generate two to 100 times more heavy metals than mergers between neutron stars and black holes. The four mergers on which they based their analysis are estimated to have occurred within the last 2.5 billion years. They conclude then, that during this period, at least, more heavy elements were produced by binary neutron star mergers than by collisions between neutron stars and black holes.

The scales could tip in favor of neutron star-black hole mergers if the black holes had high spins, and low masses. However, scientists have not yet observed these kinds of black holes in the two mergers detected to date.

Chen and her colleagues hope that, as LIGO and Virgo resume observations next year, more detections will improve the team's estimates for the rate at which each merger produces heavy elements. These rates, in turn, may help scientists determine the age of distant galaxies, based on the abundance of their various elements.

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Mystery of heavy elements in galactic cosmic rays

Scientists have used data from the Southwest Research Institute-led Magnetospheric Multiscale (MMS) mission to explain the presence of energetic heavy elements in galactic cosmic rays (GCRs). GCRs are composed of fast-moving energetic particles, mostly hydrogen ions called protons, the lightest and most abundant elements in the universe. Scientists have long debated how trace amounts of heavy ions in GCRs are accelerated.

The supernova explosion of a dying star creates massive shockwaves that propagate through the surrounding space, accelerating ions in their path to very high energies, creating GCRs. How heavy ions are energized and accelerated is important because they affect the redistribution of mass throughout the universe and are essential for the formation of even heavier and more chemically complex elements. They also influence how we perceive astrophysical structures.

"Heavy ions are thought to be insensitive to an incoming shockwave because they are less abundant, and the shock energy is overwhelmingly consumed by the preponderance of protons. Visualize standing on a beach as waves move the sand under your feet, while you remain in place," said SwRI's Dr. Hadi Madanian, the lead author of the paper about this research published in Astrophysical Journal Letters. "However, that classical view of how heavy ions behave under shock conditions is not always what we have seen in high-resolution MMS observations of the near-Earth space environment."

Shock phenomena also occur in the near-Earth environment. The Sun's magnetic field is carried through interplanetary space by the supersonic solar wind flow, which is obstructed and diverted by the Earth's magnetosphere, a bubble of protection around our home planet. This interaction region is called the bow shock due to its curved shape, comparable to the bow waves that occur as a boat travels through water. The Earth's bow shock forms at a much smaller scale than supernova shocks. However, at times, conditions of this small shock resemble those of supernova remnants. The team used high-resolution in-situ measurements from the MMS spacecraft at the bow shock to study how heavy ions are accelerated.

"We observed intense amplification of the magnetic field near the bow shock, a known property associated with strong shocks such as supernova remnants. We then analyzed how different ion species behaved as they encountered the bow shock," Madanian said. "We found that these enhanced fields significantly modify the trajectory of heavy ions, redirecting them into the acceleration zone of the shock."

While this behavior was not expected to occur for heavy ions, the team identified direct evidence for this process in alpha particles, helium ions that are four times more massive than protons and have twice the charge.

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