Astronomers discovered another asteroid sharing Mars’ orbit. These types of asteroids are called trojans‚ and they orbit in two clumps‚ one ahead of and one behind the planet. But the origins of the Mars trojans are unclear. Can this new discovery help explain where they came from? There are now 14 known Mars Trojans and the name of the newest one is 2023 FW14. They’re in two groups‚ one 60 degrees ahead and one 60 degrees behind Mars. These are the Lagrange 4 and Lagrange 5 points. Most of the Mars trojans are at the L5 point‚ and this newly discovered one is the second one found at the L4 point. New research published in the journal Astronomy and Astrophysics presents the discovery. Its title is “Dynamics of 2023 FW14‚ the second L4 Mars trojan‚ and a physical characterization using the 10.4 m Gran Telescopio Canarias.” The lead author is Raul de la Fuente Marcos from the Earth Physics and Astrophysics Department at the Universidad Complutense de Madrid. Scientists aren’t certain where the Mars trojans came from. Other trojans like the Jupiter trojans may have been captured by Jupiter in the Solar System’s early years. Or Jupiter may have captured them later when it migrated. But Mars is a much less massive planet‚ and astronomers aren’t certain if Mars can capture trojans the same way Jupiter does. The Mars trojans could be as old as the Jupiter trojans‚ but some evidence suggests otherwise. The dozen or more trojans at the Mars L5 point seem to be a family from the same collision. The family is called Eureka‚ and their spectra indicate an olivine-rich composition. Olivine is relatively rare in the main asteroid belt. That’s led some researchers to suggest that the L5 Mars trojans are debris from an ancient impact between Mars‚ where olivine is common‚ and a planetesimal. The two L4 Mars trojans are different. They don’t have the same spectra as the L5 trojans‚ but the pair do show some similarities in their spectra‚ so a common origin for these two is a possibility. In this paper‚ the researchers set out to determine 2023 FW14’s origins. They used the Gran Telescopio Canarias for their work. It’s a 10.4-meter telescope in Spain’s Canary Islands with an attached instrument called the OSIRIS camera spectrograph. 2023 FW14’s spectrum places it in the same class as an Xc-type asteroid. The X-type name contains several different types of asteroids with similar spectra but probably with different compositions. Xc-types are a sub-class of the X-types that are intermediate between C-type asteroids‚ the most common type of asteroid in the Solar System‚ and the uncommon K-type asteroids. This graph from the research shows the spectrum of 2023 FW14 and several spectra of the other known L4 Mars Trojan (121514) 1999 UJ7. Orange shows 2023 FW14‚ with the red line representing the best asteroid taxonomical match‚ the Xc-type. Teal‚ blue‚ and green show different published spectra of 1999 UJ7. The gray area fills the entire domain between the mean B-type and D-type classes of asteroids. Image Credit: Marcos et al. 2024. The researchers also used N-body simulations to try to understand the new asteroid’s resonance with Mars. Trojans follow what are known as tadpole orbits. Tadpole orbits are influenced by Earth’s gravity‚ which causes objects to librate or accelerate or decelerate alternately. Tadpole orbits are complex. Asteroids on these orbits exchange large amounts of energy and angular momentum with a planet moving in a circular orbit. Tadpole loops are made of multiple overlapping epicyclic loops. This video illustrates the tadpole orbit followed by an asteroid in Jupiter’s L4‚ not Mars’ L4‚ but the concept is the same. 2023 FW14 has a higher orbital eccentricity and lower inclination than Mars’ other L4 trojan. This means that it occupies an unstable region and orbits at the whim of several different resonances. That instability means that in a few million years‚ it’ll likely be ejected. The researchers calculated its size as approximately 318 metres (+493/-199.) That makes it one of the smallest known trojans so far. As for its origins‚ the authors say that there are two possibilities. Its long-term behaviour‚ including its past‚ suggests that it was captured from the Near Earth Asteroid (NEA) population of Mars-crossing asteroids. But it could be a fragment of another trojan‚ as well‚ one that is so far undiscovered‚ or one that is no longer a trojan. Spectral data suggests something else. Both of the L4 asteroids appear to be more primitive than Mars’ L5 trojans. 2023 FW14’s spectrum also supports the idea that it’s a captured Mars-crossing NEA. However‚ that data isn’t as clear‚ according to the authors‚ and can’t be used to rule out the other hypothesis‚ which is that the asteroid formed in situ. “Although incomplete‚ the data support the interpretation of 2023 FW14 as an interloper captured from the Mars-crossing NEA population‚ but they cannot be used to reject the competing hypothesis that 2023 FW14 was produced in situ‚” they write. Whatever its origins are‚ the researchers calculate that 2023 FW14 has about 10 million years before it’s ejected from its trojan orbit. It’s a temporary trojan‚ and this discovery could prove that Mars trojans can be temporarily captured‚ something that so far has been unproven. The post An Asteroid Found Sharing the Orbit of Mars appeared first on Universe Today.

If you have a view of the southern celestial sky‚ on a clear night you might see two clear smudges of light set off a bit from the great arch of the Milky Way. They are the Large and Small Magellanic Clouds‚ and they are the most visible of the dwarf galaxies. Dwarf galaxies are small galaxies that typically cluster around larger ones. The Milky Way‚ for example‚ has nearly two dozen dwarf galaxies. Because of their small size‚ they can be more significantly affected by dark matter. Their formation may even have been triggered by the distribution of dark matter. So they can be an excellent way to study this mysterious unseen material. In a recent study‚ a team looked at dwarf galaxies to see exactly what they would reveal about dark matter. Specifically‚ they were interested in how dark matter might interact with itself. One idea about dark matter particles is that when they collide with each other they could emit gamma-ray light. This would mean that the central regions of galaxies should show evidence of gamma radiation without a clear astrophysical source. There have been some studies looking for gamma rays within our own galaxy‚ but the results have been inconclusive. This new study focused on dwarf galaxies because they are smaller and therefore less likely to obscure gamma-ray light from colliding dark matter. There are also plenty of dwarf galaxies within our local group. Using 14 years of archival data from the Fermi-Large Area Telescope (LAT)‚ the team looked at 50 dwarf galaxies. Overall they didn’t find strong evidence of gamma-ray emissions from any of the galaxies‚ but in 7 of them they found a small statistical excess at around 2? – 3?. To be definitive we’d like to see it at a level of 5?‚ so this result is far from conclusive. But if we take the energy levels of the excess at face value‚ it would put the mass of dark matter particles around 30 – 50 GeV or 150 ? 230 GeV‚ depending on the way dark matter might decay. By comparison‚ protons have a mass of about 1 GeV. So once again a study of dark matter fails to discover the elusive particles. But as with earlier studies‚ this research narrows down what dark matter might be. Specifically‚ the study rules out certain mass ranges for dark matter more than ever before. It’s yet another small step toward solving the mystery of dark matter. Reference: McDaniel‚ Alex‚ et al. “Legacy analysis of dark matter annihilation from the Milky Way dwarf spheroidal galaxies with 14 years of Fermi-LAT data.” Physical Review D 109.6 (2024): 063024. The post Dwarf Galaxies Could be the Key to Explaining Dark Matter appeared first on Universe Today.

The only thing worse than drifting through space for an eternity is doing it alone. Observations with the Hubble Space Telescope show that brown dwarfs that once had companions suffer that fate. Binary brown dwarfs that were once bound to each other tend to drift apart as time passes. Brown dwarfs are one of Nature’s genre-busters. They refuse to be pigeonholed into our definitions. They’re neither stars nor planets and are sometimes referred to as failed stars. They gathered too much mass to be called planets but not enough to be called stars. They live in a kind of twilight zone‚ where they go about their business fusing only deuterium. This fusion is enough to emit some light and warmth but nothing that rivals an actual main sequence star. Brown dwarfs are too big to be planets but not quite massive enough to be stars. Credit: NASA/JPL-Caltech Brown dwarfs are not necessarily brown in colour. Their name comes from their size. They’re in between white dwarf stars and “dark” planets‚ if that makes sense. Brown dwarfs fade over time as they deplete their deuterium. The warmest ones are red or orange‚ and the cooler ones are magenta or even black to our eyes. Astronomers think brown dwarfs will cool down forever. Most stars are in binary pairs‚ and brown dwarfs are no exception. Up to 85% of stars in the Milky Way are in binary pairs‚ according to some research. But the Hubble shows that when it comes to brown dwarfs‚ divorce is more common than in Hollywood. In a survey of stars in our solar neighbourhood‚ the HST didn’t find any binary brown dwarfs with widely separated companions. That implies that brown dwarfs can’t maintain their binary relationships‚ probably because they’re simply not massive enough. “This is the best observational evidence to date that brown dwarf pairs drift apart over time‚” said Clémence Fontanive‚ the lead author of a new paper. “We could not have done this kind of survey and confirmed earlier models without Hubble’s sharp vision and sensitivity.” The new paper is in the Monthly Notices of the Royal Astronomical Society. Its title is “An HST survey of 33 T8 to Y1 brown dwarfs: NIR photometry and multiplicity of the coldest isolated objects.” The lead author is Clémence Fontanive from the Trottier Institute for Research on Exoplanets‚ Université de Montréal‚ Canada. Brown dwarfs occupy spectral types M‚ L‚ T‚ and Y‚ and the numbers in the title are sub-types. “Our survey confirms that widely separated companions are extremely rare among the lowest-mass and coldest isolated brown dwarfs‚ even though binary brown dwarfs are observed at younger ages. This suggests that such systems do not survive over time‚” said lead author Fontanive. The researchers worked with a set of 33 nearby ultracool brown dwarfs‚ a sample large enough to be statistically significant. The survey was designed to be deeply sensitive to low-mass objects that could be companions. Though the survey unearthed some potential companions for some of the brown dwarfs‚ further analysis showed they’re background objects. The fact that they detected no binary companions allowed the researchers to “place stringent upper limits on the occurrence of binary companions‚” according to the paper. But the lack of detection also means they can’t place any constraints or limits on the binary orbital separation or mass ratio distributions of this population. This survey only examined older‚ dimmer brown dwarfs. Younger brown dwarfs can still have their binary partners. Studies of younger brown dwarfs show that around eight percent of them have binary partners. In fact‚ the younger the brown dwarf‚ the more likely it is to have a binary partner. “These findings marginally confirm the idea that the decrease in binary frequencies with later type observed across the stellar and substellar regimes for the field population might continue throughout the substellar mass range down to the very lowest masses‚ as illustrated in Fig. 12‚” the authors explain. This is Figure 12 from the study‚ and it illustrates the rate of brown dwarf binary companions as brown dwarfs age. The binary frequency is shown on the y-axis‚ and the spectral type‚ which relates to age‚ is on the x-axis. Each mark inside the graph plots the results of a study of brown dwarf companions‚ including this one in pink. The graph clearly shows that younger brown dwarfs have more binary companions than aged brown dwarfs. Image Credit: Fontanive et al. 2024. In a press release‚ lead author Fontanive explained why brown dwarfs lose their binary partners over time. “Our Hubble survey offers direct evidence that these binaries that we observe when they’re young are unlikely to survive to old ages; they’re likely going to get disrupted. When they’re young‚ they’re part of a molecular cloud‚ and then‚ as they age‚ the cloud disperses. As that happens‚ things start moving around‚ and stars pass by each other. Because brown dwarfs are so light‚ the gravitational hold tying wide binary pairs is very weak‚ and bypassing stars can easily tear these binaries apart‚” said Fontanive. The authors point out that there’s an inevitable weakness in their results. Since brown dwarfs are so small and dim‚ the usual methods of detecting companions don’t work. Astronomers rely on the transit method and the radial velocity method to detect companion objects‚ whether planets orbiting stars or other objects in relationships with one another. But their inherent dimness makes detecting transits very difficult. Their inherent low masses likewise make the radial velocity ineffective. That leaves them with the direct optical detection method the researchers in this study relied on. There could be a better way. “Astrometry might provide a more viable alternative approach to search for companions to faint brown dwarfs‚ although very little work has been carried out on this side‚ and no systems have been reported this way so far‚” the authors write in the conclusion. When it comes to astrometry‚ the ESA’s Gaia spacecraft is the standard-bearer. It has the power to detect Jupiter-mass companions when they’re orbiting main sequence stars‚ but detecting binary brown dwarfs is still difficult‚ even for Gaia. Gaia has detected many brown dwarfs‚ but for now‚ it’s up to direct imaging to detect brown dwarf binary pairs. In this study‚ direct imaging found no widely separated binary companions despite the HST’s effectiveness. “With an excellent sensitivity and completeness to companions on wide orbital separations‚ our survey robustly confirms that wide companions are extremely rare in the Galactic field around the lowest mass systems‚” the authors write. Any companions would need to be inside the 1 to 5 AU limit of this work. “Our results‚ with no detection of wide companions out of 33 observed objects‚ reinforce the idea that the widely separated binaries with very low-mass primaries identified in young associations have no counterparts among isolated objects in the Solar neighbourhood‚” the authors conclude. The post Brown Dwarf Pairs Drift Apart in Old Age appeared first on Universe Today.

If we could detect a clear‚ unambiguous biosignature on just one of the thousands of exoplanets we know of‚ it would be a huge‚ game-changing moment for humanity. But it’s extremely difficult. We simply aren’t in a place where we can be certain that what we’re detecting means what we think or even hope it does. But what if we looked at many potential worlds at once? It’s assumptions that plague us. Every chemical we detect in an exoplanet atmosphere‚ even with the powerful JWST‚ is accompanied by a set of assumptions. We simply don’t know enough yet for it to be any other way. This puts us in a difficult place‚ considering the magnitude of the question we’re trying to answer: is there life beyond Earth? “A fundamental goal of astrobiology is to detect life outside of Earth‚” write the authors of a new paper. It’s titled “An Agnostic Biosignature Based on Modeling Panspermia and Terraformation‚” and it’s available on the pre-press site arxiv.org. The authors are Harrison B. Smith and Lana Sinapayen. Smith is from the Earth-Life Science Institute at the Tokyo Institute of Technology in Japan‚ and Sinapayen is from the Sony Computer Science Laboratories in Kyoto‚ Japan. The fundamental goal that the pair of authors give voice to is a difficult one to reach. “This proves to be an exceptional challenge outside of our solar system‚ where strong assumptions must be made about how life would manifest and interact with its planet‚” the authors explain. We only know how Earth’s biosphere works‚ and we’re left to assume what similarities there might be with other planets. We don’t have any consensus about how biospheres might be able to work. We’re not completely ignorant‚ as chemistry and physics make some things possible and others impossible. But we’re not an authority on biospheres. Scientists are pretty good at modelling things and trying to generate useful answers‚ as well as generating relevant questions they might not have thought of without models. In this work‚ the pair of authors took a different approach to understanding life on other worlds and what effort we can make to detect it. “Here we explore a model of life spreading between planetary systems via panspermia and terraformation‚” the authors write. “Our model shows that as life propagates across the galaxy‚ correlations emerge between planetary characteristics and location and can function as a population-scale agnostic biosignature.” The word ‘agnostic’ is key here. It means that they’re aiming to detect a biosignature that’s independent of the assumptions we’re normally saddled with. “This biosignature is agnostic because it is independent of strong assumptions about any particular instantiation of life or planetary characteristic—by focusing on a specific hypothesis of what life may do rather than what life may be‚” the authors explain. This approach is different. They analyze planets by their observed characteristics and then cluster them based on those observations. Then‚ they examine the spatial extent of the clusters themselves. That leads to a way to prioritize individual planets for their potential to harbour life. Panspermia and terraforming play key roles. We know that rocks can travel between worlds‚ and that’s called lithopanspermia. Powerful impacts on Mars lofted rocks into space‚ some of which eventually fell to Earth. If dormant organisms like spores could survive the journey‚ it’s at least feasible that life could spread this way. Panspermia is the idea that life is spread throughout the galaxy‚ or even the Universe‚ by asteroids‚ comets‚ and even minor planets. Credit: NASA/Jenny Mottor Terraforming is self-explanatory for the most part. It’s the effort to engineer a world to be more habitable. If there are other technological‚ space-faring civilizations out there‚ one useful working assumption is that they’ll eventually terraform other worlds if they last long enough. In any case‚ even non-technological life can purposefully alter its environment. (Sit and watch beavers sometime.) The authors make an interesting point regarding panspermia and terraforming. They’re both things that life already does‚ kind of. “Ultimately‚ our postulates of panspermia and terraformation are merely well-understood hallmarks of life (proliferation via replication and adaptation with bi-directional environmental feedback)‚ escalated to the planetary scale‚ and executed on an interstellar scale‚” they write. The authors’ model shows that the way planets are distributed around stars‚ along with their other characteristics‚ could be evidence of life without even attempting to detect chemical biosignatures. This is the agnostic part of their work. It’s more powerful than a one-planet-at-a-time struggle to detect biosignatures‚ as plagued as that effort is by assumptions. Single planets with detected biosignatures can always be explained away by something anomalous. But that’s harder to do in this agnostic method. “Hypothesizing that life spreads via panspermia and terraformation allows us to search for biosignatures while forgoing any strong assumptions about not only the peculiarities of life (e.g.‚ its metabolism) and planetary habitability (e.g.‚ requiring surface liquid water) but even the potential breadth of structure and chemical complexity underpinning living systems‚” the authors explain. This figure from the study helps illustrate the authors’ work. A shows a target planet selection‚ where an initial planet and its composition are randomly selected. This planet represents a terraformed parent planet. B shows the simulation run beginning with the initial parent planet‚ showing how nearby planets will be terraformed to more closely match the parent planet. C shows how each terraformed planet will retain some of its differences‚ about 10% in the researchers’ model. Image Credit: Smith and Sinapayen‚ 2024. We’re accustomed to thinking about specific chemicals‚ and the types of atmospheres exoplanets have to determine the presence of biosignatures. But that’s not how this works. This model is agnostic‚ so it’s not really about specific chemical biosignatures. It’s more about the patterns and clusters we could detect in populations of planets that could signal the presence of life via panspermia and terraforming. Terraformed planets can be identified from their clustering‚ the authors claim. That’s because when they’re terraformed‚ the planets need to reflect the originating planet. This figure from the research shows how simulated terraformed planets would appear clustered on a graph. This is a projection of 3D planet locations in the 2D X-Y plane and the earliest time step where the researchers detect a cluster of planets meeting their selection criteria. True terraformed planets have a blue fill‚ while planets detected by their selection method have a red outline. Image Credit: Smith and Sinapayen‚ 2024. There are obstacles to this method that limit its usefulness and implementation. According to the authors‚ they need to identify “… specific ways in which better understanding astrophysical and planetary processes would improve our ability to detect life‚” the authors write. But even without more specifics‚ the method is thought-provoking and creative. In the end‚ the authors’ model and method lead to a novel way to think about life’s hierarchies and how these hierarchies might be replicated on other planets. If this method is strengthened and more fully developed‚ who knows what it might lead to? The post Life Might Be Difficult to Find on a Single Planet But Obvious Across Many Worlds appeared first on Universe Today.

In a win for planetary scientists‚ and planetary geologists in particular‚ it was announced at the recent 55th Lunar and Planetary Science Conference (LPSC) in Texas earlier this month that NASA’s VERITAS mission to the planet Venus has been reinstated into NASA’s Fiscal Year 2025 (FY25) budget with a scheduled launch date of 2031‚ with the unofficial announcement coming on the first day of the conference‚ March 11‚ 2024‚ and being officially announced just a few days later. This comes after VERITAS experienced a “soft cancellation” in March of last year when NASA revealed its FY24 budget‚ providing VERITAS only $1.5 million‚ which was preceded by the launch of VERITAS being delayed a minimum of three years due to findings from an independent review board in November 2022. VERITAS is back in the budget!! ??? The project will get going full swing this fall (FY25). We’re looking at a 31 launch (TBC). Thanks to everyone who’s supported our return to Venus!! It’s going to be fabulous ?— Sue Smrekar (@SueSmrekar) March 11‚ 2024 Dr. Sue Smrekar‚ who is the Principal Investigator for the VERITAS mission‚ announcing during LPSC 2024 that VERITAS has been reinstated. Here‚ Universe Today speaks with Dr. Paul Byrne‚ who is an Associate Professor of Earth‚ Environmental‚ and Planetary Sciences at Washington University in St. Louis‚ and a huge proponent of exploring Venus‚ about his thoughts on VERITAS being reinstated‚ the alleged events that led to VERITAS’ reinstatement‚ his experience between VERITAS being postponed to now‚ and his thoughts on what science VERITAS hopes to accomplish at Venus. So‚ what are his thoughts on VERITAS being reinstated? “First and foremost‚ it’s relief‚” Dr. Byrne tells Universe Today. “Although VERITAS wasn’t cancelled per se‚ we in the planetary community weren’t sure if or where VERITAS would be reinstated. Although it’s disappointing to have a selected mission be delayed‚ it’s a very positive sign that VERITAS is back in the budget. Of course‚ there’s a flip side to this development: the mission’s stablemate‚ DAVINCI‚ has itself been delayed. It’s clear that the prevailing budget situation at NASA is very tough right now‚ and lots of missions are feeling it. Unfortunately‚ with two Venus missions in the pipeline‚ the Venus community is feeling this budget toughness most acutely.” After years of being proposed as a NASA Discovery mission‚ VERITAS was officially selected in June 2021‚ along with DAVINCI (previously known as DAVINCI+) to explore the second planet from the Sun like never before. While VERITAS will be tasked with producing new surface maps of Venus‚ DAVINCI was tasked with conducting atmospheric science‚ as debate continues over the potential habitability of Venus’ atmosphere. With an initial scheduled launch date between 2028 and 2030‚ the November 2022 findings pushed this back to 2031‚ only to result in the “soft cancellation” just months later. With the planetary science community pushing for VERITAS to be reinstated over the last 12 months‚ what led to VERITAS being reinstated? “A major part of it was‚ in my view‚ strong advocacy not only by the Venus community but by the planetary science community at large‚” Dr. Byrne tells Universe Today. “Other advisory groups—volunteer groups charged with collating and representing to NASA the needs of a given portion of the planetary science community—voiced very loud‚ strong support for VERITAS beyond just the Venus community‚ in a wonderful example of community-wide support. Groups such as The Planetary Society also lent their voice to supporting VERITAS. That advocacy was noticed by NASA HQ and by Congress‚ which played no small role in getting VERITAS back into the budget.” While not officially a member of the VERITAS mission team‚ Dr. Byrne has a myriad of publications about Venus‚ including as a co-author on five LPSC 2024 studies that discussed lava flow cooling‚ Venus’ potential habitability as an analog for other planets‚ predicting tectonic activity‚ predicting future volcanic activity‚ and current active volcanism. Additionally‚ Dr. Byrne has expressed his continued support via social media for both the second planet from the Sun and the VERITAS and DAVINCI missions throughout their respective journeys‚ and specifically when they were selected in June 2021. Therefore‚ what kind of emotional roller coaster has he experienced between VERITAS being canceled and now? “It’s so hard to see a mission being selected for a science target NASA hasn’t been to in forty years‚ only for it to be postponed through no fault of the mission team itself‚” Dr. Byrne tells Universe Today. “And it’s wonderful that we now know VERITAS will fly‚ even if it’s later than originally planned. But I’m keenly aware‚ as someone who’s not a member of the VERITAS team‚ that the highs and lows I’ve experienced are nothing compared with those of the team itself‚ who put their heart and soul (and at least three attempts!) to get VERITAS selected. Better late than never‚ but better on time than late. Still‚ we make do with the circumstances we face!” As Dr. Byrne alluded to‚ the last NASA mission to Venus was the Magellan spacecraft‚ which was launched on May 4‚ 1989‚ from the Space Shuttle Atlantis during the STS-30R mission and arrived at Venus on August 10‚ 1990. Over the course of the next four years‚ Magellan used its synthetic aperture radar to map the entire surface of Venus since the extreme thickness of Venus’ clouds prevents direct imaging of the surface. After Magellan’s first imaging cycle that lasted 243 days‚ it successfully mapped 83.7 percent of Venus’ surface‚ which increased to 96 percent after its second cycle and completed its mission at 98 percent after its third cycle. As a result‚ Magellan images identified a myriad of features across the Venusian surface‚ including volcanic evidence‚ tectonic activity‚ lava channels‚ pancake-shaped domes‚ and stormy winds across the surface. Therefore‚ with VERIATS equally tasked with mapping Venus’ surface‚ what science does VERITAS hope to achieve at Venus? “VERITAS will carry a radar to Venus to obtain the most comprehensive‚ accurate‚ and highest-resolution radar image and topographic data ever acquired for the second planet‚” Dr. Byrne tells Universe Today. “VERITAS will also be able to acquire spectral measurements of the surface in the infrared‚ offering us new insight into the composition of the planet’s surface materials. Moreover‚ the topographic and geodetic data VERITAS will return will in turn be used to help calibrate data from DAVINCI and the ESA EnVision mission‚ too.” What new discoveries will VERITAS make about Venus in the coming years and decades? Only time will tell‚ and this is why we science! As always‚ keep doing science &; keep looking up! The post NASA’s VERITAS Mission Breathes New Life appeared first on Universe Today.

Using ESA’s Gaia spacecraft‚ astronomers have tracked down two streams of stars that likely formed the foundation of the Milky Way. Named “Shakti and Shiva‚” the two streams contain about 10 million stars‚ all of which are 12 to 13 billion years old and likely came together even before the spiral arms and disk were formed. These star streams are all moving in roughly similar orbits and have similar compositions. Astronomers think they were probably separate galaxies that merged into the Milky Way shortly after the Big Bang.‚ “What’s truly amazing is that we can detect these ancient structures at all‚” said lead author Khyati Malhan of the Max Planck Institute for Astronomy (MPIA) in Heidelberg‚ Germany‚ in an ESA press release. “The Milky Way has changed so significantly since these stars were born that we wouldn’t expect to recognize them so clearly as a group – but the unprecedented data we’re getting from Gaia made it possible.” Astrometry Data Gaia uses astrometry — the precise measurements of the positions and movements of stars and other celestial bodies – and is building the largest‚ most precise three-dimensional map of our Galaxy by surveying nearly two billion objects. With Gaia’s data‚ the researchers were able to determine the orbits of individual stars in the Milky Way‚ as well as determine their content and composition. These ancient stars are all moving in very similar orbits and the structure of the two different star streams stood out because their stars contained a certain chemical composition. “Shakti and Shiva populations possess an unconventional combination of orbital and abundance properties that have not been observed previously‚” the researchers wrote in their paper‚ published in the Astrophysical journal.  By compiling very detailed chemical abundance patterns for each‚ the astronomers determined these stars were the oldest stars in the galaxy‚ all born before the disc of the Milky Way had formed. The components of the Milky Way Galaxy. This artist’s impression shows our roughly 13 billon-year-old ‘barred spiral galaxy’ that is home to a few hundred billion stars. Credit: Left: NASA/JPL-Caltech; right: ESA; layout: ESA/ATG medialab. “The stars there are so ancient that they lack many of the heavier metal elements created later in the Universe’s lifetime‚” said co-author Hans-Walter Rix‚ also of MPIA and the lead ‘galactic archaeologist’ in this research‚ which began in 2022. “These heavy metals are those forged within stars and scattered through space when they die. The stars in our galaxy’s heart are metal-poor‚ so we dubbed this region the Milky Way’s ‘poor old heart’. Until now‚ we had only recognized these very early fragments that came together to form the Milky Way’s ancient heart. With Shakti and Shiva‚ we now see the first pieces that seem comparably old but located further out. These signify the first steps of our galaxy’s growth towards its present size.” While the two streams are similar‚ they aren’t exactly the same. Shakti stars orbit a little further from the Milky Way’s center and in more circular orbits than Shiva stars. The streams are named two divine beings from Hindu philosophy who worked together to create the Universe. Because of Gaia’s ability to provide data to create incredibly detailed celestial maps‚ the researchers were able to build a dynamical map of that includes the two star streams plus other known components that have played a role in our galaxy’s formation. “Revealing more about our galaxy’s infancy is one of Gaia’s goals‚ and it’s certainly achieving it‚” said Timo Prusti‚ Project Scientist for Gaia at ESA. “We need to pinpoint the subtle yet crucial differences between stars in the Milky Way to understand how our galaxy formed and evolved. This requires incredibly precise data – and now‚ thanks to Gaia‚ we have that data. As we discover surprise parts of our galaxy like the Shiva and Shakti streams‚ we’re filling the gaps and painting a fuller picture of not only our current home‚ but our earliest cosmic history.” Further reading:ESA press releasePaper: Shiva and Shakti: Presumed Proto-Galactic Fragments in the Inner Milky Way The post Gaia Finds Ancient Streams of Stars That Formed the Milky Way appeared first on Universe Today.

In the constellation of Orion‚ there is a brilliant bluish-white star. It marks the right foot of the starry hunter. It’s known as Rigel‚ and it is the most famous example of a blue supergiant star. Blue supergiants are more than 10‚000 times brighter than the Sun‚ with masses 16 – 40 times greater. They are unstable and short-lived‚ so they should be rare in the galaxy. While they are rare‚ blue supergiants aren’t as rare as we would expect. A new study may have figured out why. We aren’t entirely sure how these massive stars form‚ though one idea is that they occur when a massive main sequence star passes through an interstellar cloud. By capturing gas and dust from the cloud‚ a star can shift off the main sequence to become a blue supergiant. Another idea is that they may form within stellar nurseries with a mass as great as 300 Suns. As a result‚ they quickly burn so brightly that they never become true main-sequence stars. Both of these models predict that blue supergiants are much more rare than the number we observe. This new study starts by noting that blue supergiants‚ particularly the smaller ones known as B-type supergiants‚ are rarely seen with companion stars. This is odd since most massive stars form as part of a binary or multiple system. The authors propose that B-type blue supergiants aren’t often in binary systems because they typically are the product of binary mergers. The team simulated a range of models where a giant main-sequence star has a smaller close-orbiting companion and then looked at what would result if the two stars merged. They then compared the results to observations of 59 young blue supergiant stars in the Large Magellanic Cloud. They found that not only can these mergers produce blue supergiants in the mass range of the Magellanic stars‚ but the spectra of the simulated mergers match the spectra of the 59 blue supergiants. This strongly suggests that many if not most B-type blue supergiants are the result of stellar mergers. In the future‚ the team would like to carry this work further to see how blue supergiants evolve into neutron stars and black holes. This could help explain the type of mergers observed by gravitational wave observatories such as LIGO and Virgo. Reference: Menon‚ Athira‚ et al. “Evidence for Evolved Stellar Binary Mergers in Observed B-type Blue Supergiants.” The Astrophysical Journal Letters 963.2 (2024): L42. The post Merging Stars Can Lead to Blue Supergiants appeared first on Universe Today.

Even with all we’ve learned about Mars in recent years‚ it doesn’t stack up against all we still don’t know and all we hope to find out. We know that Mars was once warm and wet‚ a conclusion that was less certain a couple of decades ago. Now‚ scientists are working on uncovering the details of Mars’s ancient water. New research shows that the Gale Crater‚ the landing spot for NASA’s MSL Curiosity‚ held water for a longer time than scientists thought. Life needs water‚ and it needs stability. So‚ if Gale Crater held water for a long time‚ it strengthens the idea that Mars could’ve supported life. We know that Gale Crater is an ancient paleolake‚ and this research suggests that the region could’ve been exposed to water for a longer duration than thought. But was it liquid water? The research is titled “Ice? Salt? Pressure? Sediment deformation structures as evidence of late-stage shallow groundwater in Gale crater‚ Mars.” It’s published in the journal Geology‚ and the lead author is Steven Banham. Banham is from the Imperial College of London’s Department of Earth‚ Science‚ and Engineering. The research centers on desert sandstone that Curiosity found. We know that water played a role in shaping the Martian surface. Multiple rovers and orbiters have given us ample evidence of that. Orbital images show clear examples of ancient deltas. We also have many images of sedimentary rock‚ with its tell-tale layered structure‚ laid down in the presence of water. But beyond the initial creation of Martian sandstone‚ the details of the rock can tell scientists about what happened long after it formed. The Eberswalde delta near Holden Crater on Mars is considered the ‘smoking gun’ for evidence of liquid water on Mars. By NASA/JPL/Malin Space Science Systems This research focuses on Gale Crater and the landforms within it. Mount Sharp (aka Aeolis Mons) is the dominant feature in the crater and rises 5.5 km or about 18‚000 feet. It’s made up of sedimentary layers that have been eroded over time. But it has substructures that show its detailed history. One structure overlays Mount Sharp and post-dates Mount Sharp’s erosion. It’s characterized by the accumulation of aeolian strata under arid conditions. That means windborne deposits instead of waterborne deposits. So scientists can tell that there was a wet period during which fluviolacustrine sediments built Mt. Sharp. They can also tell that a dry period followed‚ during which wind-borne sediment created the overlying structure. That’s what you’d expect to find if the story ended here: Mars was wet‚ then it wasn’t. “Surprisingly‚ we found that these wind-deposited layers were contorted into strange shapes‚ which suggests the sand had been deformed shortly after being laid down. These structures point to the presence of water just below the surface.”Amelie Roberts‚ study co-author‚ Imperial College London’s Department of Earth Science and Engineering. But scientists found something odd in the overlying windborne sandstone: deformed layers that could only have been formed in the presence of water. “The sandstone revealed that water was probably abundant more recently‚ and for longer‚ than previously thought – but by which process did the water leave these clues?” Banham said in a press release. That’s more difficult to determine. “This water might have been pressurized liquid‚ forced into and deforming the sediment; frozen‚ with the repeat freezing and thawing process causing the deformation; or briny‚ and subject to large temperature swings‚” Banham said. “What’s clear is that behind each of these potential ways to deform this sandstone‚ water is the common link.” There’s a generally accepted understanding of Martian water among scientists. By the middle of Mars’ Hesperian Period‚ the planet lost its water. The Hesperian’s boundaries in time are uncertain‚ but it’s generally thought of as the transition from the heavy bombardment period to the dry Mars we know today. The Hesperian could’ve ended between 3.2 and 2.0 billion years ago. The Noachian preceded it‚ and the Amazonian followed it. This research presents a new wrinkle. It suggests that Mars had abundant subsurface water toward the end of the Hesperian. The evidence is in MSL Curiosity’s images of different sedimentary rocks on Gale Crater’s Mt. Sharp. “When sediments are moved by flowing water in rivers‚ or by the wind blowing‚ they leave characteristic structures which can act like fingerprints of the ancient processes that formed them‚” said Banham. MSL Curiosity slowly worked its way up Mt. Sharp‚ studying the rocks at different elevations as it ascended. As expected‚ it found younger rocks the higher it went. Eventually‚ it reached the Stimson formation. The Stimson formation is the remnant of an ancient windborne desert dune field. An analysis of Curiosity’s images shows that Stimson formed after Mt. Sharp when Mars was thought to be dry. But Stimson isn’t entirely uniform. One of its features is named the Feòrachas structure‚ and it contains features that were clearly influenced by the presence of water. “Usually‚ the wind deposits sediment in a very regular‚ predictable way‚” said study co-author Amelie Roberts‚ a PhD candidate from Imperial College London’s Department of Earth Science and Engineering. “Surprisingly‚ we found that these wind-deposited layers were contorted into strange shapes‚ which suggests the sand had been deformed shortly after being laid down. These structures point to the presence of water just below the surface.” This image from the study shows part of the Feorachas structure with undeformed features. Water played no role in shaping them. B shows wind-ripple laminations. The image also shows cross laminations‚ which are the result of additional sediments deposited by wind. Image Credit: Banham et al. 2024‚ NASA/JPL-Caltech/MSSS In the Brackenberry outcrop feature‚ the sedimentary rocks show evidence of deformation by water. There are laminations in various states of deformity‚ becoming more pronounced in the feature geologists call the cusp core. In the cusp core‚ wind-ripple laminations bend toward the vertical and become incoherent. This image from the research shows some features that are deformed by the presence of water. Vertical‚ incoherent sedimentary lines in the cusp core‚ oversteepened laminations‚ and vertically deformed laminations are all evidence of the presence of water. Image Credit: Banham et al. 2024‚ NASA/JPL-Caltech/MSSS The authors explain that there are three mechanisms that can explain the deformed features‚ and they all involve water. They’re also not mutually exclusive. High-pressure water could’ve overcome the strength of the rock and deformed it. Large ice deposits on top of the structure could’ve caused deformation‚ as could freeze/thaw cycles of water inside the rock. The third explanation involves sediment rock weakly bound together by evaporites. Thermal expansion and contraction of the evaporites can deform the rock. This image from the research shows more examples of fluidization structures. A shows a feature named Up Helly Aa‚ and B is a zoomed-in image showing up warping and vertical laminations. C shows the Lamington feature‚ and D is a zoomed-in image showing more deformed laminations. Image Credit: Banham et al. 2024‚ NASA/JPL-Caltech/MSSS “The layers of sediment in the crater reveal a shift from a wet environment to a drier one over time – reflecting Mars’ transition from humid and habitable environment to inhospitable desert world‚” said co-author Roberts. “But these water-formed structures in the desert sandstone show that water persisted on Mars much later than previously thought.” Mars is no exoplanet‚ but it’s inadvertently teaching us a lot about our quest to understand exoplanets and habitability. “Determining whether Mars and other planets were once able to support life has been a major driving force for planetary research for more than half a century‚” said Dr. Banham. “Our findings reveal new avenues for exploration – shedding light on Mars’ potential to support life and highlighting where we should continue hunting for new clues.” “Our finding extends the timeline of water persisting in the region surrounding Gale crater‚ and so the whole region could have been habitable for longer than previously thought‚” said Amelie. Maybe one day in the far distant future‚ one of our rovers on a distant exoplanet will flip over a rock and watch something scuttle away. It’s easy to imagine. But Mars is an instructive example. If it remained habitable for longer than we thought‚ it was likely only marginally inhabitable. We can’t say for sure‚ but complex life seems to be out of the question. This should prepare humanity for what we can expect to find in our quest for habitable exoplanets. There are a bewildering number of variables that go into making Earth the living oasis that it is. We’re much more likely to stumble on other planets like Mars‚ which were once habitable and maybe even harboured simple life. If Earth’s long-lived habitability is the outlier‚ and Mars’ marginal‚ interrupted habitability is more likely‚ we can expect to find many planets like it that were once alive but are now long dead.   The post Mars’ Gale Crater was Filled with Water for Much Longer Than Anyone Thought appeared first on Universe Today.

Saturn’s moon‚ Enceladus‚ is a gleaming beacon that captivates our intellectual curiosity. Its clean‚ icy surface makes it one of the most reflective objects in the entire Solar System. But it’s what’s below that ice that really gets scientists excited. Under its icy shell is an ocean of warm‚ salty water‚ and the ESA says investigating the moon should be a top priority. Enceladus is Saturn’s sixth-largest moon. It’s only about 500 km (300 miles) in diameter. But despite its small size‚ it may harbour a buried ocean containing 15 million cubic km of water. (Earth has about 1.4 billion cubic kilometres of water.) The Cassini spacecraft spotted plumes of water coming from under the ice‚ and ever since then‚ scientists have hungered for a closer look at the moon. The European Space Agency (ESA) aims to give them one. “The mission concepts that we have recommended would provide tremendous scientific return‚ driving forward our knowledge‚ and would be fundamental for the successful detection of biosignatures on icy moons.”Dr. Zita Martins‚ astrobiologist at Instituto Superior Técnico. The ESA’s long-term plan for exploring the Solar System is called Voyage 2050. In 2021‚ the ESA settled on an overarching theme for their Voyage 2050 activities called “Moons of the Giant Solar System Planets.” The ESA struck a committee of top planetary scientists to flesh out their ideas‚ and that committee laid out the priorities. According to them‚ the ESA should focus on one of the ocean moons and explore its habitability by investigating links between its environment and its interior. The ESA should also search for signs of life‚ either extant or ancient‚ and try to identify any surface chemistry that could enable life. Dr. Zita Martins‚ an astrobiologist at Instituto Superior Técnico‚ chaired the team of planetary scientists. “The mission concepts that we have recommended would provide tremendous scientific return‚ driving forward our knowledge‚ and would be fundamental for the successful detection of biosignatures on icy moons‚” said Dr. Martins. “I am very happy to have been part of this process‚ seeing first-hand the early steps that will potentially lead to the investigation of the moons of the giant planets by ESA‚” said Dr. Martins. “The search for habitable conditions and for signatures of life in the Solar System is challenging from a science and technology point of view but very exciting!” But which moon should the ESA focus on? Candidates include Jupiter’s moon Europa and Saturn’s moons‚ Enceladus and Titan. Strong scientific cases can be made for each of these‚ as each one hosts liquid water. Europa‚ Enceladus‚ and Titan all have subsurface oceans‚ and all three are targets for potential exploration. Image Credits: NASA But each moon is unique‚ and any mission to either of these moons would be uniquely complex. And expensive. Working alongside the science committee was a team of engineers from the ESA’s Concurrent Design Facility (CDF). Their job was to think ahead to the types of technologies that would be needed‚ and if they would be possible within a couple of decades. “We commissioned three CDF studies focused on the most promising moons: Jupiter’s Europa and Saturn’s Enceladus and Titan‚” elaborates Dr Frederic Safa‚ head of ESA’s Future Missions Department. “The team of scientists worked closely with the CDF engineers on the objectives of each study. The outcomes helped pin down what can be done with the resources that we will have in the 2040s.” One had to be chosen‚ and the ESA chose Enceladus. Titan is second on the list‚ and Europa is third. (NASA is launching a mission to Europa in October 2024‚ and the ESA launched its JUICE mission to Jupiter last year.) Enceladus has many qualities that attract planetary scientists interested in habitability: it has liquid water‚ an energy source‚ and some specific chemicals. Data from the Cassini spacecraft is behind this global infrared mosaic of Saturn’s moon Enceladus. The intriguing ‘tiger stripes’ feature is prominent. Image Credit: NASA/JPL-Caltech/University of Arizona/LPG/CNRS/University of Nantes/Space Science Institute Enceladus’ plumes are salty and chemically rich. Along with sodium‚ chlorine‚ and carbon trioxide‚ there are nitrogen‚ carbon dioxide‚ and hydrocarbons like methane and formaldehyde. There are also some simple organic compounds and larger organic molecules like benzene. The water is kept liquid by the warmth from tidal heating. As Enceladus orbits Saturn‚ the gigantic planet tugs on the moon and deforms it. Each time it does‚ friction heats the moon. The moon also has a rocky core‚ and some of that rock is probably melted‚ creating magma chambers. It all adds up to an icy moon with a liquid ocean where the water interacts with the rock core‚ a critical part of it all. And it’s all kept warm despite a lack of radionuclides. Unlike Earth’s core‚ Enceladus has no radionuclides to generate warmth. Instead‚ tidal heating keeps the moon warm and drives the movement of water. Image Credit: Surface: NASA/JPL-Caltech/Space Science Institute; interior: LPG-CNRS/U. Nantes/U. Angers. Graphic composition: ESA Anybody who follows planetary science news knows some of this‚ and they know that Enceladus is begging to be explored. A mission to Enceladus would be great for everybody interested in planetary science but would be especially rewarding for the ESA itself. “An investigation into signs of past or present life around Saturn has never been achieved before. It would guarantee ESA leadership in planetary science for decades to come‚” said ESA Director of Science‚ Prof. Carole Mundell. The ESA launched its JUICE (Jupiter Icy Moons Explorer) mission one year ago. It’ll reach the Jovian system in 2031 and explore Jupiter’s moons Europa‚ Ganymede‚ and Callisto. Together with an eventual mission to Enceladus and NASA’s Europa Clipper mission‚ we’re on the cusp of learning an awful lot more about icy ocean moons. The mission won’t be launched until the early 2040s and would take about a decade to reach its target. It could explore the Saturn system with far more technologically advanced science instruments than its predecessor‚ Cassini-Huygens. It could mimic that mission by exploring the system before a grand finale took it up close to Enceladus for our best-ever look at the icy ocean moon. The science team developing the mission concept says that collecting a sample from Enceladus’ plumes is a must. A lander could do it‚ though that introduces an order of magnitude more complexity and expense. But an orbiter could do it too‚ by flying through the plumes‚ collecting a sample‚ and examining it in an onboard lab. The discovery of ocean moons with icy shells has changed our understanding of planetary science‚ our Solar System‚ habitability‚ and the search for life. If there are this many ocean moons in our Solar System‚ how many are there out there in the Milky Way? Learning more about Enceladus‚ Europa‚ and the rest could teach us a lot about life in the Universe and potential exomoon habitability. The post Europe Has Big Plans for Saturn’s Moon Enceladus appeared first on Universe Today.