SPACE/COSMOS
FIAT LUX
Flickers and flares: Milky Way’s central black hole constantly bubbles with light
James Webb Space Telescope reveals ongoing, rapid-fire light show
video:
Using NASA's James Webb Space Telescope, Northwestern astrophysicists gained the longest, most detailed glimpse yet of the supermassive black hole at the center of the Milky Way. They found the black hole's accretion disk emits a constant stream of flares with no periods of rest.
This video shows the 2.1 micron data taken on April 7, 2024.
Credit: Farhad Yusef-Zadeh/Northwestern University
The supermassive black hole at the center of the Milky Way appears to be having a party — and it is weird, wild and wonderful.
Using NASA’s James Webb Space Telescope (JWST), a Northwestern University-led team of astrophysicists has gained the longest, most detailed glimpse yet of the void that lurks in middle of our galaxy.
The swirling disk of gas and dust (or accretion disk) orbiting the central supermassive black hole, called Sagittarius A*, is emitting a constant stream of flares with no periods of rest, the researchers found. While some flares are faint flickers, lasting mere seconds, other flares are blindingly bright eruptions, which spew daily. There also are even fainter flickers that surge for months at a time. The level of activity occurs over a wide range of time — from short interludes to long stretches.
The new findings could help physicists better understand the fundamental nature of black holes, how they interact with their surrounding environments and the dynamics and evolution of our own galactic home.
The study will be published on Tuesday (Feb. 18) in The Astrophysical Journal Letters.
“Flares are expected to happen in essentially all supermassive black holes, but our black hole is unique,” said Northwestern’s Farhad Yusef-Zadeh, who led the study. “It is always bubbling with activity and never seems to reach a steady state. We observed the black hole multiple times throughout 2023 and 2024, and we noticed changes in every observation. We saw something different each time, which is really remarkable. Nothing ever stayed the same.”
An expert on the Milky Way’s center, Yusef-Zadeh is a professor of physics and astronomy at Northwestern’s Weinberg College of Arts and Sciences. The international team of coauthors includes Howard Bushouse of the Space Telescope Science Institute, Richard G. Arendt of NASA, Mark Wardle of Macquarie University in Australia, Joseph Michail of Harvard & Smithsonian and Claire Chandler of the National Radio Astronomy Observatory.
Random fireworks
To conduct the study, Yusef-Zadeh and his team used the JWST’s near infrared camera (NIRCam), which can simultaneously observe two infrared colors for long stretches of time. With the imaging tool, the researchers observed Sagittarius A* for a total of 48 hours — in 8-to-10-hour increments across one year. This enabled scientists to track how the black hole changed over time.
While Yusef-Zadeh expected to see flares, Sagittarius A* was more active than he anticipated. Simply put: the observations revealed ongoing fireworks of various brightness and durations. The accretion disk surrounding the black hole generated five to six big flares per day and several small sub-flares in between.
“In our data, we saw constantly changing, bubbling brightness,” Yusef-Zadeh said. “And then boom! A big burst of brightness suddenly popped up. Then, it calmed down again. We couldn’t find a pattern in this activity. It appears to be random. The activity profile of the black hole was new and exciting every time that we looked at it.”
Two separate processes at play
Although astrophysicists do not yet fully understand the processes at play, Yusef-Zadeh suspects two separate processes are responsible for the short bursts and longer flares. If the accretion disk is a river, then the short, faint flickers are like small ripples that fluctuate randomly on the river’s surface. The longer, brighter flares, however, are more like tidal waves, caused by more significant events.
Yusef-Zadeh posits that minor disturbances within the accretion disk likely generate the faint flickers. Specifically, turbulent fluctuations within the disk can compress plasma (a hot, electrically charged gas) to cause a temporary burst of radiation. Yusef-Zadeh likens the event to a solar flare.
“It’s similar to how the sun’s magnetic field gathers together, compresses and then erupts a solar flare,” he explained. “Of course, the processes are more dramatic because the environment around a black hole is much more energetic and much more extreme. But the sun’s surface also bubbles with activity.”
Yusef-Zadeh attributes the big, bright flares to magnetic reconnection events — a process where two magnetic fields collide, releasing energy in the form of accelerated particles. Traveling at velocities near the speed of light, these particles emit bright bursts of radiation.
“A magnetic reconnection event is like a spark of static electricity, which, in a sense, also is an ‘electric reconnection,’” Yusef-Zadeh said.
Double vision
Because the JWST’s NIRCam can observe two separate wavelengths (2.1 and 4.8 microns) at the same time, Yusef-Zadeh and his collaborators were able to compare how the flares’ brightness changed with each wavelength. Yusef-Zadeh said capturing light at two wavelengths is like “seeing in color instead of black and white.” By observing Sagittarius A* at multiple wavelengths, he captured a more complete and nuanced picture of its behavior.
Yet again, the researchers were met with a surprise. Unexpectedly, they discovered events observed at the shorter wavelength changed brightness slightly before the longer-wavelength events.
“This is the first time we have seen a time delay in measurements at these wavelengths,” Yusef-Zadeh said. “We observed these wavelengths simultaneously with NIRCam and noticed the longer wavelength lags behind the shorter one by a very small amount — maybe a few seconds to 40 seconds.”
This time delay provided more clues about the physical processes occurring around the black hole. One explanation is that the particles lose energy over the course of the flare — losing energy quicker at shorter wavelengths than at longer wavelengths. Such changes are expected for particles spiraling around magnetic field lines.
Aiming for an uninterrupted look
To further explore these questions, Yusef-Zadeh hopes to use the JWST to observe Sagittarius A* for a longer period of time. He recently submitted a proposal to observe the black hole for an uninterrupted 24 hours. The longer observation run will help reduce noise, enabling the researchers to see even finer details.
“When you are looking at such weak flaring events, you have to compete with noise,” Yusef-Zadeh said. “If we can observe for 24 hours, then we can reduce the noise to see features that we were unable to see before. That would be amazing. We also can see if these flares show periodicity (or repeat themselves) or if they are truly random.”
The study, “Non-stop variability of Sgr A* using JWST at 2.1 and 4.8 micron wavelengths: Evidence for distinct populations of faint and bright variable emission,” was supported by NASA and the National Science Foundation.
Journal
The Astrophysical Journal Letters
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Non-stop variability of Sgr A* using JWST at 2.1 and 4.8 micron wavelengths: Evidence for distinct populations of faint and bright variable emission
Article Publication Date
18-Feb-2025
Einstein Probe catches X-ray odd couple
image:
Einstein Probe captured the X-ray flash from a very elusive celestial pair, consisting of a big, hot star, more than 10 times larger than our Sun, and a small compact white dwarf, with a mass similar to our star.
Scientists think that the couple started off together, as a better-matched binary pair consisting of two rather big stars, six and eight times more massive than our Sun.
The bigger star exhausted its nuclear fuel earlier and started to expand, shedding matter to its companion. First, gas in its puffed-up outer layers got pulled in by the companion; then its remaining outer shells got ejected, forming an envelop around the two stars, which later became a disc, and finally dissolved.
By the end of this drama, the companion star had grown to be 12 times the mass of the Sun, while the outstripped core of the other had collapsed to become a white dwarf of just over one solar mass. Now, it is the turn of the white dwarf to steal and gobble up material from the outer layers of the Be star.
view moreCredit: ESA
The odd celestial couple consists of a big, hot star, more than 10 times larger than our Sun, and a small compact white dwarf, with a mass similar to our star. Only a handful of these systems have been found so far. And this the first time scientists could track the X-ray light coming from such a curious pair from its initial sudden flare-up to its fading away.
On 27 May 2024, the Wide-field X-ray Telescope (WXT) on Einstein Probe spotted X-rays coming from within our neighbour galaxy, the Small Magellanic Cloud (SMC). To uncover the origin of this new celestial beacon, labelled EP J0052, scientists pointed Einstein Probes’s Follow-up X-ray Telescope in that direction.
WXT’s observations also triggered NASA’s Swift and NICER X-ray telescopes to point to the newly discovered object. ESA’s XMM-Newton followed up 18 days after the trigger.
“We were chasing fleeting sources, when we came across this new spot of X-ray light in the SMC. We realised that we were looking at something unusual, that only Einstein Probe could catch,” says Alessio Marino, a postdoctoral researcher at the Institute of Space Sciences (ICE-CSIC), Spain and lead author of the new study published today.
“This is because, among current telescopes monitoring the X-ray sky, WXT is the only one that can see lower energy X-rays with sufficient sensitivity to catch the novel source.”
Initially, the scientists thought EP J0052 might be a well-known type of binary system that shines in X-rays. These pairs consist of a neutron star devouring up material from a massive star companion. Yet, there was something in the data telling a different story…
A rare discovery
Thanks to Einstein Probe catching the novel source right from its initial flash, scientists could analyse batches of data from different instruments. They examined how the light varied across a range of X-ray wavelengths, over six days, and teased out some of the elements present in the exploding material, such as nitrogen, oxygen and neon. The analysis delivered crucial clues.
“We soon understood that we were dealing with a rare discovery of a very elusive celestial couple” explains Alessio. “The unusual duo consists of a massive star that we call a Be star, weighting 12 times the Sun, and a stellar ‘corpse’ known as a white dwarf, a compact and hyper-dense object, with a mass similar to that of our star.”
The two stars closely orbit each other, and the white dwarf’s intense gravitational field pulls matter from its companion. As more and more material (mainly hydrogen) rains down on the compact object, its strong gravitation compresses it, until a runaway nuclear explosion is initiated. This creates a bright flash of light across a wide range of wavelengths from visible light to UVs and X-rays.
At first sight, the existence of this duo is puzzling. Massive stars of type Be burn fast through their reserve of nuclear fuel. Their lives are fierce and short, spanning about 20 million years. Its companion is (usually) the collapsed remnant of a star similar to our Sun that in isolation would live for several billions of years.
Since binary stars typically form together, how can the supposedly short-lived star still be shining bright, while the alleged long-lived one has already died?
There is an explanation.
A tale of two stars
Scientists think that the couple started off together, as a better-matched binary pair consisting of two rather big stars, six and eight times more massive than our Sun.
The bigger star exhausted its nuclear fuel earlier and started to expand, shedding matter to its companion. First, gas in its puffed-up outer layers got pulled in by the companion; then its remaining outer shells got ejected, forming an envelop around the two stars, which later became a disc, and finally dissolved.
By the end of this drama, the companion star had grown to be 12 times the mass of the Sun, while the outstripped core of the other had collapsed to become a white dwarf of just over one solar mass. Now, it is the turn of the white dwarf to steal and gobble up material from the outer layers of the Be star.
“This study gives us new insights into a rarely observed phase of stellar evolution, which is the result of a complex exchange of material that must have happened among the two stars,” remarks Ashley Chrimes, research fellow and X-ray astronomer at ESA. “It’s fascinating to see how an interacting pair of massive stars can produce such an intriguing outcome.”
ESA’s XMM-Newton mission’s follow-up observation in the direction of EP J0052, 18 days after Einstein Probe’s first look, did not see the signal anymore. This sets a limit on the duration of the flare, showing it to be relatively brief.
The duration of the short burst, and the presence of neon and oxygen, hint at a rather heavy type of white dwarf, likely 20% more massive than the Sun. Its mass is close to the level, called Chandrasekhar limit, above which the star would continue to implode, and become an even denser neutron star, or explode as a supernova.
Game-changing monitor
“Outbursts from a Be-white dwarf duo have been extraordinarily hard to catch, as they are best observed with low energy X-rays. The advent of Einstein Probe offers the unique chance to spot these fleeting sources and test our understanding of how massive stars evolve,” remarks Erik Kuulkers, ESA Project Scientist for Einstein Probe.
“This discovery showcases the game-changing capabilities of this mission.”
About Einstein Probe
Einstein Probe is a mission of the Chinese Academy of Science (CAS) working in partnership with the European Space Agency (ESA), the Max-Planck-Institute for extraterrestrial Physics (MPE), Germany, and the Centre National d'Études Spatiales (CNES), France. It was launched from the Xichang Satellite Launch Centre in China on 9 January 2024, and carries two instruments. The Wide-field X-ray Telescope (WXT) constantly monitors a large portion of the sky for unexpected X-rays, and the Follow-up X-ray Telescope (FXT) that homes in on the X-ray sources found by WXT for a more detailed look.
Journal
The Astrophysical Journal Letters
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Einstein Probe discovery of EPJ005245.1−722843: a rare BeWD binary in the Small Magellanic Cloud
Article Publication Date
18-Feb-2025
“Out of science fiction”: First 3D observations of an exoplanet’s atmosphere reveal a unique climate
image:
Tylos (or WASP-121b) is a gaseous, giant exoplanet located some 900 light-years away in the constellation Puppis. Using the ESPRESSO instrument on ESO’s Very Large Telescope (VLT), scientists have been able to prove into its atmosphere, revealing its 3D structure. This is the first time that this has been possible on a planet outside of the Solar System.
The atmosphere of Tylos is divided into three layers, with iron winds at the bottom, followed by a very fast jet stream of sodium, and finally an upper layer of hydrogen winds. This kind of climate has never been seen before on any planet.
view moreCredit: ESO/M. Kornmesser
Astronomers have peered through the atmosphere of a planet beyond the Solar System, mapping its 3D structure for the first time. By combining all four telescope units of the European Southern Observatory’s Very Large Telescope (ESO’s VLT), they found powerful winds carrying chemical elements like iron and titanium, creating intricate weather patterns across the planet’s atmosphere. The discovery opens the door for detailed studies of the chemical makeup and weather of other alien worlds.
“This planet’s atmosphere behaves in ways that challenge our understanding of how weather works — not just on Earth, but on all planets. It feels like something out of science fiction,” says Julia Victoria Seidel, a researcher at the European Southern Observatory (ESO) in Chile and lead author of the study, published today in Nature.
The planet, WASP-121b (also known as Tylos), is some 900 light-years away in the constellation Puppis. It’s an ultra-hot Jupiter, a gas giant orbiting its host star so closely that a year there lasts only about 30 Earth hours. Moreover, one side of the planet is scorching, as it is always facing the star, while the other side is much cooler.
The team has now probed deep inside Tylos’s atmosphere and revealed distinct winds in separate layers, forming a map of the atmosphere’s 3D structure. It’s the first time astronomers have been able to study the atmosphere of a planet outside our Solar System in such depth and detail.
“What we found was surprising: a jet stream rotates material around the planet’s equator, while a separate flow at lower levels of the atmosphere moves gas from the hot side to the cooler side. This kind of climate has never been seen before on any planet,” says Seidel, who is also a researcher at the Lagrange Laboratory, part of the Observatoire de la Côte d'Azur, in France. The observed jet stream spans half of the planet, gaining speed and violently churning the atmosphere high up in the sky as it crosses the hot side of Tylos. “Even the strongest hurricanes in the Solar System seem calm in comparison,” she adds.
To uncover the 3D structure of the exoplanet's atmosphere, the team used the ESPRESSO instrument on ESO’s VLT to combine the light of its four large telescope units into a single signal. This combined mode of the VLT collects four times as much light as an individual telescope unit, revealing fainter details. By observing the planet for one full transit in front of its host star, ESPRESSO was able to detect signatures of multiple chemical elements, probing different layers of the atmosphere as a result.
“The VLT enabled us to probe three different layers of the exoplanet’s atmosphere in one fell swoop,” says study co-author Leonardo A. dos Santos, an assistant astronomer at the Space Telescope Science Institute in Baltimore, United States. The team tracked the movements of iron, sodium and hydrogen, which allowed them to trace winds in the deep, mid and shallow layers of the planet’s atmosphere, respectively. “It’s the kind of observation that is very challenging to do with space telescopes, highlighting the importance of ground-based observations of exoplanets,” he adds.
Interestingly, the observations also revealed the presence of titanium just below the jet stream, as highlighted in a companion study published in Astronomy and Astrophysics. This was another surprise since previous observations of the planet had shown this element to be absent, possibly because it’s hidden deep in the atmosphere.
“It’s truly mind-blowing that we’re able to study details like the chemical makeup and weather patterns of a planet at such a vast distance,” says Bibiana Prinoth, a PhD student at Lund University, Sweden, and ESO, who led the companion study and is a co-author of the Nature paper.
To uncover the atmosphere of smaller, Earth-like planets, though, larger telescopes will be needed. They will include ESO’s Extremely Large Telescope (ELT), which is currently under construction in Chile’s Atacama Desert, and its ANDES instrument. “The ELT will be a game-changer for studying exoplanet atmospheres,” says Prinoth. “This experience makes me feel like we’re on the verge of uncovering incredible things we can only dream about now.”
More information
This research was presented in a paper published in the journal Nature titled “Vertical structure of an exoplanet’s atmospheric jet stream” (doi:10.1038/s41586-025-08664-1).
The team is composed of: Julia V. Seidel (European Southern Observatory, Santiago, Chile [ESO Chile]; Laboratoire Lagrange, Observatoire de la Côte d’Azur, CNRS, Université Côte d’Azur, Nice, France [Lagrange]), Bibiana Prinoth (ESO Chile and Lund Observatory, Division of Astrophysics, Department of Physics, Lund University, Lund, Sweden [ULund]), Lorenzo Pino (INAF-Osservatorio Astrofisico di Arcetri, Florence, Italy), Leonardo A. dos Santos (Space Telescope Science Institute, Baltimore, USA, Johns Hopkins University, Baltimore, USA), Hritam Chakraborty (Observatoire de Genève, Département d’Astronomie, Université de Genève, Versoix, Switzerland [UNIGE]), Vivien Parmentier (Lagrange), Elyar Sedaghati (ESO Chile), Joost P. Wardenier (Département de Physique, Trottier Institute for Research on Exoplanets [IREx], Université de Montréal, Canada), Casper Farret Jentink (UNIGE), Maria Rosa Zapatero Osorio (Centro de Astrobiología, CSIC-INTA, Madrid, Spain), Romain Allart (IREx), David Ehrenreich (UNIGE), Monika Lendl (UNIGE), Giulia Roccetti (European Southern Observatory, Garching bei München, Germany; Meteorologisches Institut, Ludwig-Maximilians-Universität München, Munich, Germany), Yuri Damasceno (Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, Porto, Portugal [IA-CAUP], Departamento de Fisica e Astronomia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal [FCUP]; ESO Chile), Vincent Bourrier (UNIGE), Jorge Lillo-Box (Centro de Astrobiología (CAB); CSIC-INTA, Madrid, Spain), H. Jens Hoeijmakers (ULund), Enric Pallé (Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain [IAC]; Departamento de Astrofísica, Universidad de La Laguna, La Laguna, Tenerife, Spain [IAC-ULL]), Nuno Santos (IA-CAUP and FCUP), Alejandro Suàrez Mascareño (IAC and IAC-ULL), Sergio G. Sousa (IA-CAUP), Hugo M. Tabernero (Departamento de Física de la Tierra y Astrofísica & IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos de la UCM), Universidad Complutense de Madrid, Spain), and Francesco A. Pepe (UNIGE).
The companion research, uncovering the presence of titanium, was published in the journal Astronomy & Astrophysics in a paper titled “Titanium chemistry of WASP-121 b with ESPRESSO in 4-UT mode” (doi: 10.1051/0004-6361/202452405)
The team behind this paper is composed of: Bibiana Prinoth (European Southern Observatory, Santiago, Chile [ESO Chile] and Lund Observatory, Division of Astrophysics, Department of Physics, Lund University, Lund, Sweden [ULund]), Julia V. Seidel (ESO Chile; Laboratoire Lagrange, Observatoire de la Côte d’Azur, CNRS, Université Côte d’Azur, Nice, France [Lagrange]), H. Jens Hoeijmakers (ULund), Brett M. Morris (Space Telescope Science Institute, Baltimore, USA), Martina Baratella (ESO Chile), Nicholas W. Borsato (ULund, School of Mathematical and physical Sciences, Macquarie University, Sydney, Australia), Yuri Damasceno (Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, Porto, Portugal [IA-CAUP], Departamento de Fisica e Astronomia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal [FCUP]; ESO Chile), Vivien Parmentier (Lagrange), Daniel Kitzmann (University of Bern, Physics Institute, Division of Space Research & Planetary Sciences, Bern, Switzerland), Elyar Sedaghati (ESO Chile), Lorenzo Pino (INAF-Osservatorio Astrofisico di Arcetri, Florence, Italy), Francesco Borsa (INAF-Osservatorio Astronomico di Brera, Merate, Italy), Romain Allart (Département de Physique, Trottier Institute for Research on Exoplanets [IREx], Université de Montréal, Canada), Nuno Santos (IA-CAUP and FCUP), Michal Steiner (Observatoire de l'Université de Genève, Versoix, Switzerland), Alejandro Suàrez Mascareño (Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, La Laguna, Tenerife, Spain), Hugo M. Tabernero (Departamento de Física de la Tierra y Astrofísica & IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos de la UCM), Universidad Complutense de Madrid, Spain) and Maria Rosa Zapatero Osorio (Centro de Astrobiologia, CSIC-INTA, Madrid, Spain).
The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration for astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, Czechia, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.
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Journal
Nature
Dwarf planet Ceres: Building blocks of life delivered from space
The dwarf planet is a bizarre, cryovolcanic world. However, the organic deposits discovered on its surface so far are unlikely to originate from its interior.
Max Planck Institute for Solar System Research
image:
Surface of dwarf planet Ceres. The sites of organic material are shown as or in red boxes. The vast majority of sites are found near the Ernutet crater in the northern hemisphere.
view moreCredit: MPS
Organic molecules are among the necessary inventory of life-friendly worlds. On Earth, the compounds of carbon, hydrogen and – in smaller quantities – other elements form the basic building blocks of all life. In recent years, researchers have found such molecules at great distances from the Sun: on trans-Neptunian objects, comets, and far-away asteroids. These bodies are thought to be largely unaltered remnants from the early days of the Solar System. The building blocks of life may therefore have been part of their “basic configuration” from the very beginning and possibly reached the inner Solar System only later.
For the current study, the researchers looked for previously unknown deposits of organic material on dwarf planet Ceres. With its location in the middle of the asteroid belt between the orbits of Mars and Jupiter, the body is neither clearly native to the inner nor the outer Solar System. According to earlier studies, this location could even be its birthplace. Scientists are therefore interested in the origin of Ceres’s organic components. Did they originate locally in the asteroid belt? Or did they arrive later?
Searching for Organics from afar
Evidence of deposits of organic material was already found during the early stages of the Dawn mission. The Dawn spacecraft reached Ceres in March 2015 and accompanied it for about three and a half years. During this time, the scientific camera system and the spectrometer on board scanned the entire surface of the dwarf planet. Potential patches of organic material can be detected from the camera data: the brightness of the light reflected from these areas increases noticeably with increasing wavelength. The spectrometer splits the light into many more wavelengths than the camera and can therefore prove or disprove the presence of organics. Unfortunately, remote data is not sufficient to identify individual types of molecules beyond doubt. However, it is certain that the discovered deposits consist of organic compounds that have a chain-like structure. Researchers refer to such molecules as aliphatic hydrocarbons.
The authors of the current study have now used artificial intelligence to comb the entire surface of the dwarf planet for traces of aliphatic organic molecules. “Sites of such organic molecules are actually rare on Ceres, and devoid of any cryovolcanic signatures” says first author Ranjan Sarkar from the MPS, summarizing the results. The vast majority of deposits can be found along the edge or near the large Ernutet crater in the northern hemisphere of the dwarf planet. Only three are located at a greater distance from it. Two patches were not previously known. A closer look at the geological structures at the locations of the organic material allows further conclusions. “At none of the deposits do we find evidence of current or past volcanic or tectonic activity: no trenches, canyons, volcanic domes or vents. Furthermore, there are no deep impact craters nearby,” says Martin Hoffmann from MPS.
Impacts from distant neighbors
During the Dawn mission, Ceres had turned out to be an extraordinary, cryovolcanic world. Under its surface, a watery brine is hidden, which in some places has been seeping to the surface until recently. “Of course, the first assumption is that Ceres' unique cryovolcanism has transported the organic material from the interior of the body to the surface,” says Andreas Nathues from MPS, head of the camera team. “But our results show otherwise,” he adds. At the sites of cryovolcanic activity, there is no proof of organic matter. And where organic compounds have been reliably detected, there is no evidence of deep or surface activity.
The researchers therefore argue that the impact of one or more asteroids from the outer asteroid belt introduced the organic material. Computer simulations show that these bodies are among the ones that most frequently collided with Ceres. Since the not-too-distant neighbors do not pick up much speed, only little heat is generated upon impact. Organic compounds can survive these temperatures.
“Unfortunately, Dawn can't detect all types of organic compounds,” Andreas Nathues points out. It is quite likely that building blocks of life were also formed in Ceres' underground ocean and perhaps even reached the surface – or are still doing so. “However, the organic deposits that have been reliably detected with Dawn so far likely do not originate Ceres itself,” he explains. Nathues continues by saying that a future lander mission would be needed to detect organic material from the interior of Ceres.
About the mission
NASA’s Dawn mission studied two bodies in the asteroid belt up close: the protoplanet Vesta from 2011 to 2012, and the dwarf planet Ceres from 2015 to 2018. The mission’s scientific camera system, the Dawn Framing Cameras, were developed, built, and operated during the mission under the leadership of MPS. The VIR spectrometer was provided by the Italian Space Agency ASI.
Journal
AGU Advances
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Ceres: Organic-Rich Sites of Exogenic Origin?
Advanced power semiconductors block
radiation damage and lead space industry
development!
Dr. Jae Hwa Seo of KERI is fabricating SiC Power Semiconductor Devices for Radiation Resistance Evaluation in Space Environmentsview more
Credit: Korea Electrotechnology Research Institute
The research team led by Dr. Jae Hwa Seo at Advanced Semiconductor Research Center of KERI has developed technology to evaluate radiation resistance and secure reliability of silicon carbide (SiC) power semiconductor devices in space environment.
Power semiconductors are essential components of electrical and electronic devices, regulating current flow and enabling power conversion, much like muscles control movement in the human body. While silicon (Si) is currently the most widely used material for power semiconductors in electric vehicles and space environments, wide bandgap (WBG) power semiconductors1) such as silicon carbide (SiC) and diamond, which offer higher performance and durability, are gaining significant attention as advanced alternatives.
1) Wide Band Gap power semiconductor: Power semiconductors composed of compound elements of two or more types, rather than single materials like silicon (Si). Silicon carbide (SiC) and gallium nitride (GaN) power semiconductors are representative examples. WBG power semiconductors offer significantly better performance due to their larger band gap compared to conventional power semiconductors. The most prominent example, SiC power semiconductors, can withstand voltages 10 times higher than silicon power semiconductors, operate at temperatures of hundreds of degrees Celsius, and consume less power, thereby increasing energy efficiency. When applied to electric vehicles, SiC power semiconductors can provide remarkable benefits, with up to 10% improvement in power efficiency compared to silicon.
Space radiation is considered a major cause of severe degradation in the electrical characteristics of power semiconductors installed in aircraft, exploration vehicles (rovers), and satellites. While radiation effect research is actively conducted in the United States and Europe, Korea's efforts have primarily focused on the quantitative analysis of radiation resistance in silicon power semiconductors, with limited research outcomes.
KERI has successfully developed technology to effectively evaluate the radiation resistance of SiC power semiconductors through Korea's first high-energy space environment simulation. The most crucial aspect was creating an extreme space radiation experimental environment. Space radiation comprises particles of varying energy levels, with protons making up 80–90% of the total composition. Dr. Seo's team utilized high-energy protons (100 MeV) from the accelerator facility at the Korea Atomic Energy Research Institute, and collaborated with the team led by Professor Yoon Young-jun from Andong National University, experts in the field, to implement precise radiation exposure conditions.
Under these space environment conditions, KERI systematically analyzed the effects on domestically developed SiC power semiconductors, including voltage changes, increased leakage current due to exposure, and lattice damage. Using the accumulated data, the team formulated design criteria to ensure the long-term reliability of SiC power semiconductors for space applications. The research excellence was recognized with recent publication in Radiation Physics and Chemistry, a top-tier SCI journal (top 8.7%) in NUCLEAR SCIENCE & TECHNOLOGY.
Dr. Jae Hwa Seo of KERI stated, "Setting various radiation effect parameters and testing core components in similarly simulated environments is considered a key space industry technology worldwide," adding that "this technology will be applied across various fields including aerospace, medical radiation equipment, nuclear power plants, radiation waste treatment facilities, and military/defense electronics."
The research team plans to expand the technology's scope by pursuing reliability evaluations of SiC power semiconductors under ultra-high energy (over 200MeV) radiation conditions and developing advanced radiation-resistant power semiconductors. Additionally, they are conducting research on future power semiconductors using diamond, which has the best semiconductor properties on Earth, in collaboration with Gyeongnam Province and Japanese company 'Orbray'. Their goal is to contribute to Korea's development in high-value-added aerospace industries.
Meanwhile, KERI is a government-funded research institution under the National Research Council of Science & Technology, Ministry of Science and ICT. This research was conducted as part of KERI's basic project (Development of Core Technologies for High-temperature, High-frequency, High-efficiency (3 High) Power Control Modules).
KERI's advanced power semiconductor research and development site
SiC power semiconductors developed by KERI
Credit
Korea Electrotechnology Research Institute
Radiation Physics and Chemistry
DOI
10.1016/j.radphyschem.2024.112378
Article Title
Degeneration mechanism of 30 MeV and 100 MeV proton irradiation effects on 1.2 kV SiC MOSFETs
Article Publication Date
18-Feb-2025
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