UP-led astronomy research team explores formation of giant radio galaxies

An artistic representation of a what a giant cosmic jet the size of the distance between the Milky Way and Andromeda could look like
Illustration Credit: Courtesy of University of Pretoria

Enabled by supercomputing, University of Pretoria (UP) researchers have led an international team of astronomers that has provided deeper insight into the entire life cycle (birth, growth and death) of giant radio galaxies, which resemble “cosmic fountains” – jets of superheated gas that are ejected into near-empty space from their spinning supermassive black holes.

The findings of this breakthrough study were published in the journal Astronomy & Astrophysics, and challenge known theoretical models by explaining how extragalactic cosmic fountains grows to cover such colossal distances, raising new questions about the mechanisms behind these vast cosmic structures.

The research team – which was led by astrophysicist Dr Gourab Giri, who holds a postdoctoral fellowship from the South African Radio Astronomy Observatory at UP –  consisted of Associate Professor Kshitij Thorat and Extraordinary Professor Roger Deane of UP’s Faculty of Natural and Agricultural Sciences; Prof Joydeep Bagchi of Christ University in India; Prof DJ Sailkia of the Inter-University Centre for Astronomy and Astrophysics, also in India; and Dr Jacinta Delhaize of the University of Cape Town (UCT).

This study tackles a key question in modern astrophysics: how these structures, which are larger than galaxies and are made up of black hole jets, interact over cosmological timescales with their very thin, gaseous surroundings. 

SwRI models pluto-charon formation scenario that mimics earth-moon system

Using advanced models, SwRI led new research that indicates that the formation of Pluto and Charon may parallel that of the Earth-Moon system. In the resulting 'kiss-and-captureâ regime, Pluto and Charon collide and stick together in the shape of a snowman. They rotate as one body until Pluto pushes Charon out into a stable orbit.
Image Credit: Courtesy of SwRI/Adeene Denton/Robert Melikyan

A NASA postdoctoral researcher at Southwest Research Institute has used advanced models that indicate that the formation of Pluto and Charon may parallel that of the Earth-Moon system. Both systems include a moon that is a large fraction of the size of the main body, unlike other moons in the solar system. The scenario also could support Pluto’s active geology and possible subsurface ocean, despite its location at the frozen edge of the solar system.

“We think the Earth-Moon system initiated when a Mars-sized object hit the Earth and led to the formation of our large Moon sometime later,” said Dr. Adeene Denton, who led the research, published in Nature Geoscience. “In comparison, Mars has two tiny moons that look like potatoes, while the moons of the giant planets make up a small fraction of their total systems.”

Scientists Have Detailed the Nature of the Darkest Gamma-ray Burst in the Universe

Objects like GRB 150309A tend to be located deep within galaxies.
Photo Credit: Graham Holtshausen

An international group of scientists has presented the results of a detailed spectral analysis of the instantaneous and residual X-ray emission (afterglow) from the intense two-episode dark gamma-ray burst GRB 150309A. The researchers' task was to determine the nature of the instantaneous emission and the composition of the jet ejected in the burst. In addition, based on optical and X-ray spectral analysis of the energy distribution, the researchers performed modeling of the parent galaxy of GRB 150309A to study the surrounding interstellar medium in which this outburst occurred. The results of the analysis are presented in a paper published in the journal Astronomy and Astrophysics.

A bright flash GRB 150309A lasting about 52 seconds was detected on March 9, 2015, by the Gamma-ray Burst Observatory of the Fermi Gamma-ray Space Telescope, a space observatory in low Earth orbit. The event consisted of two bursts: about 200 seconds after the first, more powerful burst, an episode of faint and quiet emission followed.

Despite the strong gamma-ray emission, optical observations with the BOOTES (Burst Observer and Optical Transient Exploration System) and GTC (Gran Telescopio Canarias) telescopes were inconclusive: only the parent galaxy of the outburst signal was detected at optical wavelengths. The X-ray afterglow of GRB 150309A was detected about 5.2 hours after the outburst by the CIRCE instrument installed on the GTC at the Spanish La Palma Observatory.

The optical inaccessibility under intense gamma-ray emission and the intense red X-ray afterglow detected in the near-infrared with CIRCE led scientists to suggest that GRB 150309A belongs to a subclass of dark bursts.

Scientists release new insight about Southern Ring Nebula

The Southern Ring Nebula, or NGC 3132, was one of the first objects observed by the James Webb Space Telescope.
Image Credit: NASA/ESA/CSA/STScI  

Planetary nebulae have been studied for centuries, but astronomers are getting new looks and a better understanding of the structures and compositions of these gaseous remnants of dying stars thanks to the ability to study objects at multiple wavelengths and dimensions.

The Southern Ring Nebula, or NGC 3132, is one such object. Rochester Institute of Technology Chester F. Carlson Center for Imaging Science and School of Physics and Astronomy Professor Joel Kastner and his team used Submillimeter Array (SMA) mapping to take a closer look at the nebula, which was one of the first cosmic objects observed by the James Webb Space Telescope soon after its deployment in 2022. The researchers found that most of the molecular gas in the nebula actually lies in an enormous, expanding ring, and further, that the nebula has a second, nearly perpendicular, expanding ring. The research findings were recently published in The Astrophysical Journal. Kastner is the founding director of RIT’s Laboratory for Multiwavelength Astrophysics.

Inspired by the JWST infrared images, which dramatically reveal how hydrogen gas in molecular form threads through the Southern Ring, Kastner and the team used SMA radio-wavelength mapping to measure both the distribution on the sky and the precise velocities of carbon monoxide gas in the nebula. The measurements establish which regions of the Southern Ring Nebula are moving toward and away from us, revealing the two rings. The team’s new SMA results support previous findings that the nebula’s present form is the result of interactions between the dying star and one or possibly two companion stars.

Astronomers discover 49 new galaxies in under three hours

The MeerKAT radio telescope, located in South Africa, enabled this discovery of 49 brand new galaxies.
Photo Credit: South African Radio Astronomy Observatory (SARAO)

An international team of astronomers has discovered 49 new gas-rich galaxies using the MeerKAT radio telescope in South Africa.

Dr Marcin Glowacki, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) in Western Australia, led the research, which aimed to study the star-forming gas in a single radio galaxy.  Although the team didn’t find any star-forming gas in the galaxy they were studying, Dr Glowacki instead discovered other galaxies while inspecting the data.

In total, the gas of 49 galaxies were detected. Dr Glowacki said this was a great example of how fantastic an instrument like MeerKAT is for finding the star-forming gas in galaxies.

The observations, which lasted less than three hours and were facilitated by IDIA (Inter-University Institute for Data Intensive Astronomy), made this discovery possible.

“I did not expect to find almost fifty new galaxies in such a short time,” Dr Glowacki said. “By implementing different techniques for finding galaxies, which are used for other MeerKAT surveys, we were able to detect all of these galaxies and reveal their gas content.”

The new galaxies have been informally nicknamed the 49ers, a reference to the 1849 California gold rush miners. Dr Glowacki views the 49 new galaxies as valuable as gold nuggets in our night sky. Many galaxies are near each other, forming galaxy groups, with several identified in one observation.

Rethinking galactic origins through heavy-element mapping challenges conventional theory

Galactic gas shows varying heavy element distribution: blue indicates scarcity, red indicates richness. Heavy elements are less abundant in gas than Galaxy.
Image Credit: T. Hayakawa/Y.Fukui, Nagoya University

A groundbreaking study of the origins of intermediate-velocity clouds (IVCs) challenges a 20-year-old theory and suggests a new era of deep-space research. Researchers at Nagoya University in Japan discovered that IVCs have much lower heavy elements than previously reported. Rather than the materials being constantly recycled like water in a fountain, their findings suggest that the particles that make the clouds originated outside our galaxy. The group published their findings in Monthly Notices of the Royal Astronomical Society. 

IVCs are a type of interstellar cloud characterized by their velocity. They are found at altitudes of thousands of light years away throughout the Milky Way. Gas clouds are important because they are sources of elements that enable star formation and the creation of planetary systems. 

In the conventional model, elements are released back into the interstellar medium when the stars die in events called supernovae. This material is then reincorporated into the gas clouds. According to this model, the heavy elements in IVCs are generated through nuclear fusion reactions and supernova explosions within our galaxy. 

Groundbreaking survey reveals secrets of planet birth around dozens of stars

This research brings together observations of more than 80 young stars that might have planets forming around them in spectacular discs. This small selection from the survey shows 10 discs from the three regions of our galaxy observed in the papers. V351 Ori and V1012 Ori are located in the most distant of the three regions, the gas-rich cloud of Orion, some 1600 light-years from Earth. DG Tau, T Tau, HP Tau, MWC758 and GM Aur are located in the Taurus region, while HD 97048, WW Cha and SZ Cha can be found in Chamaeleon I, all of which are about 600 light-years from Earth.  The images shown here were captured using the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument mounted on ESO’s Very Large Telescope (VLT). SPHERE’s state-of-the-art extreme adaptive optics system corrects for the turbulent effects of Earth’s atmosphere, yielding crisp images of the discs around stars. The stars themselves have been covered with a coronagraph — a circular mask that blocks their intense glare, revealing the faint discs around them.  The discs have been scaled to appear roughly the same size in this composition. 
Full Size Zoomable Image
Image Credit: ESO/C. Ginski, A. Garufi, P.-G. Valegård et al.

In a series of studies, a team of astronomers has shed new light on the fascinating and complex process of planet formation. The stunning images, captured using the European Southern Observatory's Very Large Telescope (ESO’s VLT) in Chile, represent one of the largest ever surveys of planet-forming discs. The research brings together observations of more than 80 young stars that might have planets forming around them, providing astronomers with a wealth of data and unique insights into how planets arise in different regions of our galaxy.

“This is really a shift in our field of study,” says Christian Ginski, a lecturer at the University of Galway, Ireland, and lead author of one of three new papers published today in Astronomy & Astrophysics. “We’ve gone from the intense study of individual star systems to this huge overview of entire star-forming regions.”

Metal scar found on cannibal star

This artist’s impression shows the magnetic white dwarf WD 0816-310, where astronomers have found a scar imprinted on its surface as a result of having ingested planetary debris.  When objects like planets or asteroids approach the white dwarf they get disrupted, forming a debris disc around the dead star. Some of this material can be devoured by the dwarf, leaving traces of certain chemical elements on its surface.   Using ESO’s Very Large Telescope, astronomers found that the signature of these chemical elements changed periodically as the star rotated, as did the magnetic field. This indicates that the magnetic fields funneled these elements onto the star, concentrating them at the magnetic poles and forming the scar seen here.
Illustration Credit: ESO/L. Calçada

When a star like our Sun reaches the end of its life, it can ingest the surrounding planets and asteroids that were born with it. Now, using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) in Chile, researchers have found a unique signature of this process for the first time — a scar imprinted on the surface of a white dwarf star. The results are published today in The Astrophysical Journal Letters.

“It is well known that some white dwarfs — slowly cooling embers of stars like our Sun — are cannibalizing pieces of their planetary systems. Now we have discovered that the star’s magnetic field plays a key role in this process, resulting in a scar on the white dwarf’s surface,” says Stefano Bagnulo, an astronomer at Armagh Observatory and Planetarium in Northern Ireland, UK, and lead author of the study.

New moons of Uranus and Neptune announced

The discovery image of the new Uranian moon S/2023 U1 using the Magellan telescope on November 4, 2023.  Uranus is just off the field of view in the upper left, as seen by the increased scattered light.  S/2023 U1 is the faint point of light in the center of the image. (There is an arrow pointing to it in the lower version of the image). The trails are from background stars. 
Image Credit: Scott Sheppard.

The Solar System has some new lunar members—the first new moon of Uranus discovered in more than 20 years, and likely the smallest, as well as two new moons of Neptune, one of which is the faintest moon ever discovered by ground-based telescopes. The discoveries were announced today by the International Astronomical Union's Minor Planet Center.

“The three newly discovered moons are the faintest ever found around these two ice giant planets using ground-based telescopes,” explained Carnegie Science’s Scott S. Sheppard. “It took special image processing to reveal such faint objects.”

The new Uranian member brings the ice giant planet’s total moon count to 28. At only 8 kilometers, it is probably the smallest of Uranus’ moons. It takes 680 days to orbit the planet. Provisionally named S/2023 U1, the new moon will eventually be named after a character from a Shakespeare play, in keeping with the naming conventions for outer Uranian satellites.

Black hole fashions stellar beads on a string

The international team used a combination of X-ray, radio, and optical data to understand how this unusual chain of star clusters formed stellar jewellery 3.8 billion light-years from Earth.
Image Credit: X-ray: NASA/CXC/SAO/O. Omoruyi et al.; Optical: NASA/ESA/STScI/G. Tremblay et al.; Radio: ASTRON/LOFAR; Image Processing: NASA/CXC/SAO/N. Wolk

One of the most powerful eruptions from a black hole ever recorded has been discovered by an international team of astronomers.

The mega-explosion, which took place billions of years ago, may help explain the formation of a pattern of star clusters resembling beads on a string, according to the study.

This stellar jewelry is located in SDSS J1531, a massive galaxy cluster 3.8 billion light-years from Earth, containing hundreds of individual galaxies and a huge reservoir of hot gas and dark matter.

At the heart of SDSS J1531, two of the cluster’s largest galaxies are colliding with one another.

These colliding giants are surrounded by a set of 19 large clusters of stars, called superclusters, arranged in an ‘S’ formation that resembles a string of beads.

The team used a combination of X-ray, radio, and optical data to understand how this unusual chain of star clusters formed.

The Radcliffe Wave is Waving

How the Radcliffe Wave moves through the backyard of our Sun (yellow dot). Blue dots are clusters of baby stars. The white line is a theoretical model by Ralf Konietzka and collaborators that explains the current shape and motion of the Wave. The magenta and green lines at the beginning show how and to what extent the Radcliffe Wave will move in the future. Background is a cartoon model of the Milky Way. 
Illustration Credit: Ralf Konietzka, Alyssa Goodman & WorldWide Telescope

CfA astronomers report oscillation of our giant, gaseous neighbor.

A few years ago, astronomers at the Center for Astrophysics | Harvard & Smithsonian (CfA) uncovered one of the Milky Way's greatest secrets: an enormous, wave-shaped chain of gaseous clouds in our sun’s backyard, giving birth to clusters of stars along the spiral arm of the galaxy we call home.

Naming this astonishing new structure the Radcliffe Wave, in honor of the Harvard Radcliffe Institute where the undulation was originally discovered, astronomers at CfA now report in Nature that the Radcliffe Wave not only looks like a wave, but also moves like one – oscillating through space much like "the wave" moving through a stadium full of fans.

"By using the motion of baby stars born in the gaseous clouds along the Radcliffe Wave," said Ralf Konietzka, the paper's lead author and a Ph.D. student at Harvard’s Kenneth C. Griffin Graduate School of Arts and Sciences and CfA, "we can trace the motion of their natal gas to show that the Radcliffe Wave is actually waving."

Scientists use Summit supercomputer to explore exotic stellar phenomena

Astrophysicists at the State University of New York, Stony Brook, and University of California, Berkeley created 3D simulations of X-ray bursts on the surfaces of neutron stars. Two views of these X-ray bursts are shown: the left column is viewed from above while the right column shows it from a shallow angle above the surface. The panels (from top to bottom) show the X-ray burst structure at 10 milliseconds, 20 milliseconds and 40 milliseconds of simulation time.
Image Credit: Michael Zingale/Department of Physics and Astronomy at SUNY Stony Brook.

Understanding how a thermonuclear flame spreads across the surface of a neutron star — and what that spreading can tell us about the relationship between the neutron star’s mass and its radius — can also reveal much about the star’s composition. 

Neutron stars — the compact remnants of supernova explosions — are found throughout the universe. Because most stars are in binary systems, it is possible for a neutron star to have a stellar companion. X-ray bursts occur when matter accretes on the surface of the neutron star from its companion and is compressed by the intense gravity of the neutron star, resulting in a thermonuclear explosion. 

Astrophysicists at the State University of New York, Stony Brook, and University of California, Berkeley, used the Oak Ridge Leadership Computing Facility’s Summit supercomputer, located at the Department of Energy’s Oak Ridge National Laboratory, to compare models of X-ray bursts in 2D and 3D. 

“We can see these events happen in finer detail with a simulation. One of the things we want to do is understand the properties of the neutron star because we want to understand how matter behaves at the extreme densities you would find in a neutron star,” said Michael Zingale, a professor in the Department of Physics and Astronomy at SUNY Stony Brook who led the project.

Astronomers identify record-breaking quasar

This artist’s impression shows the record-breaking quasar J059-4351, the bright core of a distant galaxy that is powered by a supermassive black hole. Using ESO’s Very Large Telescope (VLT) in Chile, this quasar has been found to be the most luminous object known in the Universe to date. The supermassive black hole, seen here pulling in surrounding matter, has a mass 17 billion times that of the Sun and is growing in mass by the equivalent of another Sun per day, making it the fastest-growing black hole ever known.
Illustration Credit: European Southern Observatory/M. Kornmesser

Using the European Southern Observatory’s (ESO) Very Large Telescope (VLT), astronomers have characterized a bright quasar, finding it to be not only the brightest of its kind, but also the most luminous object ever observed. Quasars are the bright cores of distant galaxies and they are powered by supermassive black holes. The black hole in this record-breaking quasar is growing in mass by the equivalent of one Sun per day, making it the fastest-growing black hole to date.

The black holes powering quasars collect matter from their surroundings in a process so energetic that it emits vast amounts of light. So much so that quasars are some of the brightest objects in our sky, meaning even distant ones are visible from Earth. As a general rule, the most luminous quasars indicate the fastest-growing supermassive black holes.

SwRI scientists find evidence of geothermal activity within icy dwarf planets

Eris and Makemake
Image Credit: Courtesy of Southwest Research Institute

A team co-led by Southwest Research Institute found evidence for hydrothermal or metamorphic activity within the icy dwarf planets Eris and Makemake, located in the Kuiper Belt. Methane detected on their surfaces has the tell-tale signs of warm or even hot geochemistry in their rocky cores, which is markedly different than the signature of methane from a comet.

“We see some interesting signs of hot times in cool places,” said SwRI’s Dr. Christopher Glein, an expert in planetary geochemistry and lead author of a paper about this discovery. “I came into this project thinking that large Kuiper Belt objects (KBOs) should have ancient surfaces populated by materials inherited from the primordial solar nebula, as their cold surfaces can preserve volatiles like methane. Instead, the James Webb Space Telescope (JWST) gave us a surprise! We found evidence pointing to thermal processes producing methane from within Eris and Makemake.”

The Kuiper Belt is a vast donut-shaped region of icy bodies beyond the orbit of Neptune at the edge of the solar system. Eris and Makemake are comparable in size to Pluto and its moon Charon. These bodies likely formed early in the history of our solar system, about 4.5 billion years ago. Far from the heat of our Sun, KBOs were believed to be cold, dead objects. Newly published work from JWST studies made the first observations of isotopic molecules on the surfaces of Eris and Makemake. These so-called isotopologues are molecules that contain atoms having a different number of neutrons. They provide data that is useful in understanding planetary evolution.

Discovery of Unexpected Ultramassive Galaxies May Not Rewrite Cosmology, But Still Leaves Questions

Infrared view of the universe captured by the James Webb Space Telescope.
Image Credit: NASA, ESA, CSA and STScI.

Ever since the James Webb Space Telescope (JWST) captured its first glimpse of the early universe, astronomers have been surprised by the presence of what appear to be more “ultramassive” galaxies than expected. Based on the most widely accepted cosmological model, they should not have been able to evolve until much later in the history of the universe, spurring claims that the model needs to be changed.

This would upend decades of established science.

“The development of objects in the universe is hierarchical. You start small and get bigger and bigger,” said Julian Muñoz, an assistant professor of astronomy at The University of Texas at Austin and co-author of a recent paper that tests changes to the cosmological model. The study concludes that revising the standard cosmological model is not necessary. However, astronomers may have to revisit what they understand about how the first galaxies formed and evolved.

Cosmology studies the origin, evolution and structure of our universe, from the Big Bang to the present day. The most widely accepted model of cosmology is called the Lambda Cold Dark Matter (ΛCDM) model or the “standard cosmological model.” Although the model is very well informed, much about the early universe has remained theoretical because astronomers could not observe it completely, if at all.

SwRI Scientists Identify Water Molecules on Asteroids for the First Time

NASA’s Stratospheric Observatory for Infrared Astronomy
Image Credit: NASA/Carla Thomas/SwRI

Using data from the retired Stratospheric Observatory for Infrared Astronomy (SOFIA) — a joint project of NASA and the German Space Agency at DLR — Southwest Research Institute scientists have discovered, for the first time, water molecules on the surface of an asteroid. Scientists looked at four silicate-rich asteroids using the FORCAST instrument to isolate the mid-infrared spectral signatures indicative of molecular water on two of them.

“Asteroids are leftovers from the planetary formation process, so their compositions vary depending on where they formed in the solar nebula,” said SwRI’s Dr. Anicia Arredondo, lead author of a Planetary Science Journal paper about the discovery. “Of particular interest is the distribution of water on asteroids, because that can shed light on how water was delivered to Earth.”

Anhydrous, or dry, silicate asteroids form close to the Sun while icy materials coalesce farther out. Understanding the location of asteroids and their compositions tells us how materials in the solar nebula were distributed and have evolved since formation. The distribution of water in our solar system will provide insight into the distribution of water in other solar systems and, because water is necessary for all life on Earth, will drive where to look for potential life, both in our solar system and beyond.

A carbon-lite atmosphere could be a sign of water and life on other terrestrial planets

In the search for extraterrestrial life, MIT scientists say a planet’s carbon-lite atmosphere, relative to its neighbors, could be a sure and detectable signal of habitability.
Image Credit: Scientific Frontline stock image.

Scientists at MIT, the University of Birmingham, and elsewhere say that astronomers’ best chance of finding liquid water, and even life on other planets, is to look for the absence, rather than the presence, of a chemical feature in their atmospheres.

The researchers propose that if a terrestrial planet has substantially less carbon dioxide in its atmosphere compared to other planets in the same system, it could be a sign of liquid water — and possibly life — on that planet’s surface.

What’s more, this new signature is within the sights of NASA’s James Webb Space Telescope (JWST). While scientists have proposed other signs of habitability, those features are challenging if not impossible to measure with current technologies. The team says this new signature, of relatively depleted carbon dioxide, is the only sign of habitability that is detectable now.

“The Holy Grail in exoplanet science is to look for habitable worlds, and the presence of life, but all the features that have been talked about so far have been beyond the reach of the newest observatories,” says Julien de Wit, assistant professor of planetary sciences at MIT. “Now we have a way to find out if there’s liquid water on another planet. And it’s something we can get to in the next few years.”

The team’s findings appear today in Nature Astronomy. De Wit co-led the study with Amaury Triaud of the University of Birmingham in the UK. Their MIT co-authors include Benjamin Rackham, Prajwal Niraula, Ana Glidden Oliver Jagoutz, Matej Peč, Janusz Petkowski, and Sara Seager, along with Frieder Klein at the Woods Hole Oceanographic Institution (WHOI), Martin Turbet of Ècole Polytechnique in France, and Franck Selsis of the Laboratoire d’astrophysique de Bordeaux.

Cosmic lights in the forest

TACC’s Frontera, the fastest academic supercomputer in the US, is a strategic national capability computing system funded by the National Science Foundation.
Photo Credit: TACC.

Like a celestial beacon, distant quasars make the brightest light in the universe. They emit more light than our entire Milky Way galaxy. The light comes from matter ripped apart as it is swallowed by a supermassive black hole. Quasar light reveals clues about the large-scale structure of the universe as it shines through enormous clouds of neutral hydrogen gas formed shortly after the Big Bang on the scale of 20 million light years across or more. 

Using quasar light data, the National Science Foundation (NSF)-funded Frontera supercomputer at the Texas Advanced Computing Center (TACC) helped astronomers develop PRIYA, the largest suite of hydrodynamic simulations yet made for simulating large-scale structure in the universe.

“We’ve created a new simulation model to compare data that exists at the real universe,” said Simeon Bird, an assistant professor in astronomy at the University of California, Riverside. 

Bird and colleagues developed PRIYA, which takes optical light data from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey (SDSS). He and colleagues published their work announcing PRIYA in the Journal of Cosmology and Astroparticle Physics (JCAP). 

Exoplanets' climate – it takes nothing to switch from habitable to hell

Runaway greenhouse effect can transform a temperate habitable planet with surface liquid water ocean into a hot steam dominated planet hostile to any life
Image Credit: (Chaverot et al., 2023). © Thibaut Roger / UNIGE

The Earth is a wonderful blue and green dot covered with oceans and life, while Venus is a yellowish sterile sphere that is not only inhospitable but also sterile. However, the difference between the two bears to only a few degrees in temperature. A team of astronomers from the University of Geneva (UNIGE), with the support of the CNRS laboratories of Paris and Bordeaux, has achieved a world’s first by managing to simulate the entirety of the runaway greenhouse process which can transform the climate of a planet from idyllic and perfect for life, to a place more than harsh and hostile. The scientists have also demonstrated that from the initial stages of the process, the atmospheric structure and cloud coverage undergo significant changes, leading to an almost-unstoppable and very complicated to reverse runaway greenhouse effect. On Earth, a global average temperature rise of just a few tens of degrees, subsequent to a slight rise of the Sun’s luminosity, would be sufficient to initiate this phenomenon and to make our planet inhabitable. These results are published in Astronomy & Astrophysics.

Long-sought binary star population found! Discovery could answer questions about hydrogen-poor supernova origins

An artist’s conception of the hydrogen being stripped from one half of a binary system, leaving a very hot, helium rich exposed core that will eventually explode as a hydrogen-poor core collapse supernova.
 Illustration Credit: Navid Marvi, courtesy of the Carnegie Institution for Science.

A team of astronomers has found a long- “missing” population of stars that could answer long-standing questions about the origins of a mysterious type of supernova. Their discovery, published in Science, could help researchers understand how hydrogen-poor core-collapse supernovae and neutron star collisions occur—major stellar events that are the source of many of the elements on the periodic table.

The project’s leaders, the University of Toronto’s Maria Drout and the Institute of Science and Technology Austria’s Ylva Götberg, met as junior researchers, and both went on to complete postdoctoral positions at the Carnegie Observatories—where the majority of this work was done—and have since moved onto assistant professor positions at their respective institutions.

Supernovae are violent stellar explosions that spew material into their cosmic surroundings, seeding the next generation of stars. But astronomers are still working to elucidate how they originate and what their various stellar progenitors look like—which differ between types of supernovae.

Drout and Götberg were particularly interested in one type of supernovae that stands out from their celestial peers for being hydrogen poor.