TL;DR
- Often portrayed as destructive monsters that hold light captive, black holes take on a less villainous role in the latest research from NASA’s Hubble Space Telescope. A black hole at the heart of the dwarf galaxy Henize 2–10 is creating stars rather than gobbling them up. The black hole is apparently contributing to the firestorm of new star formation taking place in the galaxy. The dwarf galaxy lies 30 million light-years away, in the southern constellation Pyxis.
- Astronomers discovered a black hole unlike any other. At one hundred thousand solar masses, it is smaller than the black holes we have found at the centers of galaxies, but bigger than the black holes that are born when stars explode. This makes it one of the only confirmed intermediate-mass black holes, an object that has long been sought by astronomers.
- Scientists believe they have detected a merger of two black holes with eccentric orbits. This can help explain how some of the previous black hole mergers are much heavier than previously thought possible.
- Astronomers have discovered a giant gas planet hidden from view by typical stargazing tools.
- A new study has investigated stellar mass black holes, which are black holes with masses between a few to some hundred solar masses, that originated at the end of the life of massive stars. According to the study, a remarkable amount of around 1 percent of the overall ordinary matter of the universe is locked up in stellar mass black holes. Astonishingly, the researchers have found that the number of black holes within the observable universe at present time is about 40 times 10 to the exponent 18.
- Astronomers have found three Jupiter-like exoplanets that are dangerously close to being ‘swallowed up’ by their host stars. The discovery gives new insight into how planetary systems evolve over time, helping to reveal the fate of solar systems like our own.
- Scientists measured the properties of ice-brine mixtures as cold as -145 degrees Fahrenheit to help confirm that salty water likely exists between grains of ice or sediment under the ice cap at Mars’ south pole. Laboratory measurements support oddly bright reflections detected by the MARSIS subsurface sounding radar aboard ESA’s Mars Express orbiter.
- A scientist recently set out to prove that the tiny, innermost moon of Saturn was a frozen inert satellite and instead discovered compelling evidence that Mimas has a liquid internal ocean. In the waning days of NASA’s Cassini mission, the spacecraft identified a curious libration, or oscillation, in the moon’s rotation, which often points to a geologically active body able to support an internal ocean.
- NASA’s Curiosity rover landed on Mars on Aug. 6, 2012, and since then has roamed Gale Crater taking samples and sending the results back home for researchers to interpret. Analysis of carbon isotopes in sediment samples taken from half a dozen exposed locations, including an exposed cliff, leave researchers with three plausible explanations for the carbon’s origin — cosmic dust, ultraviolet degradation of carbon dioxide, or ultraviolet degradation of biologically produced methane.
- Organic molecules found in a meteorite that hurtled to Earth from Mars were synthesized during interactions between water and rocks that occurred on the Red Planet about 4 billion years ago, according to new analysis.
- Upcoming industry events. And more!
Space industry in numbers
The global smart space market size is projected to grow from USD 9.4 billion in 2020 to USD 15.3 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 10.2% during the forecast period. The increasing venture capital funding and growing investments in smart space technology to drive market growth.
Analysts at Morgan Stanley and Goldman Sachs have predicted that economic activity in space will become a multi-trillion-dollar market in the coming decades. Morgan Stanley’s Space Team estimates that the roughly USD 350 billion global space industry could surge to over USD 1 trillion by 2040.
Space industry news
- SpaceX wins $102 million Air Force contract to demonstrate technologies for point-to-point space transportation
- JWST arrives at final orbit
- NASA foresees gap in lunar landings after Artemis 3
- ABL Space Systems rocket stage destroyed in test accident
- Pakistan is next to halt Starlink preorders
- GEO satellite operators seek multi-orbit strategies
- Satellogic completes SPAC merger
- Blue Origin to acquire Honeybee Robotics
- Xplore to fly sensors on OrbAstro nanosatellites
- NASA hosted payloads waiting for rides to orbit
- Cause of Lucy solar array deployment problem identified
- AFWERX to fund development of laser terminal that connects military aircraft with satellites
- Comtech rejects $790 million takeover offer
- Military space advocate Rep. Jim Cooper to retire from Congress
- NOAA to move new weather satellite quickly into position
- Isar Aerospace wins 10 million euro European Commission launch competition
- Federal Trade Commission blocks Lockheed Martin’s acquisition of Aerojet Rocketdyne
- Japan’s H3 rocket further delayed by engine woes
- RUAG Space enters AI partnership for satellite supercomputer
- China’s Galactic Energy raises $200 million for reusable launch vehicle development
- Space Norway restores redundancy for Svalbard ground stations
- Plus Ultra’s lunar comsats to hitch rides on ispace moon landers
- ULA launches two space surveillance satellites for U.S. Space Force
- ExoMars on schedule for September launch
- Former NASA administrator Bridenstine endorses candidate in Virginia congressional race
- Bigelow Aerospace transfers BEAM space station module to NASA
- ESA looks to space summit to endorse human spaceflight efforts
- OneWeb forges Indian distribution partnership
- Chinese satellite in near miss with Russian ASAT test debris
- National Reconnaissance Office signs agreements with five commercial radar satellite operators
- Mission Space signs on with EnduroSat to launch space weather instruments
- Sony putting camera in orbit for shutterbugs, not scientists
- Space Force is creating its own culture but will be ‘tightly coupled’ to the Air Force
- Space and national security: What to expect in 2022
- Radian Aerospace raises seed round to fund work on spaceplane
- Satellogic raises $150 million from fund led by former treasury secretary
- SpaceX passes 2,000 Starlink satellites launched
- Space Force taps Air Force Research Lab leader for key acquisition post
- ESA considering moving up radar satellite launch after Sentinel-1B malfunction
- Federal budget stalemate having ‘ripple effects’ on national security space missions
- SES absorbs SES Networks in streamlining effort
- EarthDaily taps Loft Orbital to build and operate $150 million constellation
- Raymond: Space Force in 2022 to focus on the design of a resilient architecture
- Israel to sign Artemis Accords: foreign minister
- NASA safety panel recommends agency review how it manages human spaceflight programs
- Bluestaq gets new investor to fund growth in defense and space data management
- China’s first launch of 2022 puts classified Shiyan-13 satellite into orbit
Latest research
Black-hole-triggered star formation in the dwarf galaxy Henize 2–10
by Zachary Schutte, Amy E. Reines in Nature
Often portrayed as destructive monsters that hold light captive, black holes take on a less villainous role in the latest research from NASA’s Hubble Space Telescope. A black hole at the heart of the dwarf galaxy Henize 2–10 is creating stars rather than gobbling them up. The black hole is apparently contributing to the firestorm of new star formation taking place in the galaxy. The dwarf galaxy lies 30 million light-years away, in the southern constellation Pyxis.
A decade ago this small galaxy set off debate among astronomers as to whether dwarf galaxies were home to black holes proportional to the supermassive behemoths found in the hearts of larger galaxies. This new discovery has little Henize 2–10, containing only one-tenth the number of stars found in our Milky Way, poised to play a big part in solving the mystery of where supermassive black holes came from in the first place.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.
“Ten years ago, as a graduate student thinking I would spend my career on star formation, I looked at the data from Henize 2–10 and everything changed,” said Amy Reines, who published the first evidence for a black hole in the galaxy in 2011 and is the principal investigator on the new Hubble observations.
“From the beginning I knew something unusual and special was happening in Henize 2–10, and now Hubble has provided a very clear picture of the connection between the black hole and a neighboring star forming region located 230 light-years from the black hole”.
That connection is an outflow of gas stretching across space like an umbilical cord to a bright stellar nursery. The region was already home to a dense cocoon of gas when the low-velocity outflow arrived. Hubble spectroscopy shows the outflow was moving about 1 million miles per hour, slamming into the dense gas like a garden hose hitting a pile of dirt and spreading out. Newborn star clusters dot the path of the outflow’s spread, their ages also calculated by Hubble.
This is the opposite effect of what’s seen in larger galaxies, where material falling toward the black hole is whisked away by surrounding magnetic fields, forming blazing jets of plasma moving at close to the speed of light. Gas clouds caught in the jets’ path would be heated far beyond their ability to cool back down and form stars. But with the less-massive black hole in Henize 2–10, and its gentler outflow, gas was compressed just enough to precipitate new star formation.
“At only 30 million light-years away, Henize 2–10 is close enough that Hubble was able to capture both images and spectroscopic evidence of a black hole outflow very clearly. The additional surprise was that, rather than suppressing star formation, the outflow was triggering the birth of new stars,” said Zachary Schutte, Reines’ graduate student and lead author of the new study.
Ever since her first discovery of distinctive radio and X-ray emissions in Henize 2–10, Reines has thought they likely came from a massive black hole, but not as supermassive as those seen in larger galaxies. Other astronomers, however, thought that the radiation was more likely being emitted by a supernova remnant, which would be a familiar occurrence in a galaxy that is rapidly pumping out massive stars that quickly explode.
“Hubble’s amazing resolution clearly shows a corkscrew-like pattern in the velocities of the gas, which we can fit to the model of a precessing, or wobbling, outflow from a black hole. A supernova remnant would not have that pattern, and so it is effectively our smoking-gun proof that this is a black hole,” Reines said.
Reines expects that even more research will be directed at dwarf galaxy black holes in the future, with the aim of using them as clues to the mystery of how supermassive black holes came to be in the early universe. It’s a persistent puzzle for astronomers. The relationship between the mass of the galaxy and its black hole can provide clues. The black hole in Henize 2–10 is around 1 million solar masses. In larger galaxies, black holes can be more than 1 billion times our Sun’s mass. The more massive the host galaxy, the more massive the central black hole.
Current theories on the origin of supermassive black holes break down into three categories: 1) they formed just like smaller stellar-mass black holes, from the implosion of stars, and somehow gathered enough material to grow supermassive, 2) special conditions in the early universe allowed for the formation of supermassive stars, which collapsed to form massive black hole “seeds” right off the bat, or 3) the seeds of future supermassive black holes were born in dense star clusters, where the cluster’s overall mass would have been enough to somehow create them from gravitational collapse.
So far, none of these black hole seeding theories has taken the lead. Dwarf galaxies like Henize 2–10 offer promising potential clues, because they have remained small over cosmic time, rather than undergoing the growth and mergers of large galaxies like the Milky Way. Astronomers think that dwarf galaxy black holes could serve as an analog for black holes in the early universe, when they were just beginning to form and grow.
“The era of the first black holes is not something that we have been able to see, so it really has become the big question: where did they come from? Dwarf galaxies may retain some memory of the black hole seeding scenario that has otherwise been lost to time and space,” Reines said.
Detection of a 100,000 M ⊙ black hole in M31’s Most Massive Globular Cluster: A Tidally Stripped Nucleus
by Renuka Pechetti, Anil Seth, Sebastian Kamann, Nelson Caldwell, Jay Strader, Mark den Brok, Nora Luetzgendorf, Nadine Neumayer, Karina Vogge in The Astrophysical Journal
Astronomers discovered a black hole unlike any other. At one hundred thousand solar masses, it is smaller than the black holes we have found at the centers of galaxies, but bigger than the black holes that are born when stars explode. This makes it one of the only confirmed intermediate-mass black holes, an object that has long been sought by astronomers.
“We have very good detections of the biggest, stellar-mass black holes up to 100 times the size of our sun, and supermassive black holes at the centers of galaxies that are millions of times the size of our sun, but there aren’t any measurements of black between these. That’s a large gap,” said senior author Anil Seth, associate professor of astronomy at the University of Utah and co-author of the study. “This discovery fills the gap.”
The black hole was hidden within B023-G078, an enormous star cluster in our closest neighboring galaxy Andromeda. Long thought to be a globular star cluster, the researchers argue that B023-G078 is instead a stripped nucleus. Stripped nuclei are remnants of small galaxies that fell into bigger ones and had their outer stars stripped away by gravitational forces. What’s left behind is a tiny, dense nucleus orbiting the bigger galaxy and at the center of that nucleus, a black hole.
“Previously, we’ve found big black holes within massive, stripped nuclei that are much bigger than B023-G078. We knew that there must be smaller black holes in lower mass stripped nuclei, but there’s never been direct evidence,” said lead author Renuka Pechetti of Liverpool John Moores University, who started the research while at the University of Utah. “I think this is a pretty clear case that we have finally found one of these objects.”
B023-G078 was known as a massive globular star cluster — a spherical collection of stars bound tightly by gravity. However, there had only been a single observation of the object that determined its overall mass, about 6.2 million solar masses. For years, Seth had a feeling it was something else.
“I knew that the B023-G078 object was one of the most massive objects in Andromeda and thought it could be a candidate for a stripped nucleus. But we needed data to prove it. We’d been applying to various telescopes to get more observations for many, many years and my proposals always failed,” said Seth. “When we discovered a supermassive black hole within a stripped nucleus in 2014, the Gemini Observatory gave us the chance to explore the idea.”
With their new observational data from the Gemini Observatory and images from the Hubble Space Telescope, Pechetti, Seth and their team calculated how mass was distributed within the object by modeling its light profile. A globular cluster has a signature light profile that has the same shape near the center as it does in the outer regions. B023-G078 is different. The light at the center is round and then gets flatter moving outwards. The chemical makeup of the stars changes too, with more heavy elements in the stars at the center than those near the object’s edge.
“Globular star clusters basically form at the same time. In contrast, these stripped nuclei can have repeated formation episodes, where gas falls into the center of the galaxy, and forms stars. And other star clusters can get dragged into the center by the gravitational forces of the galaxy,” said Seth. “It’s kind of the dumping ground for a bunch of different stuff. So, stars in stripped nuclei will be more complicated than in globular clusters. And that’s what we saw in B023-G078.”
The researchers used the object’s mass distribution to predict how fast the stars should be moving at any given location within the cluster and compared it to their data. The highest velocity stars were orbiting around the center. When they built a model without including a black hole, the stars at the center were too slow compared their observations. When they added the black hole, they got speeds that matched the data. The black hole adds to the evidence that this object is a stripped nucleus.
“The stellar velocities we are getting gives us direct evidence that there’s some kind of dark mass right at the center,” said Pechetti. “It’s very hard for globular clusters to form big black holes. But if it’s in a stripped nucleus, then there must already be a black hole present, left as a remnant from the smaller galaxy that fell into the bigger one.”
The researchers are hoping to observe more stripped nuclei that may hold more intermediate mass black holes. These are an opportunity to learn more about the black hole population at the centers of low-mass galaxies, and to learn about how galaxies are built up from smaller building blocks.
“We know big galaxies form generally from the merging of smaller galaxies, but these stripped nuclei allow us to decipher the details of those past interactions,” said Seth.
Eccentricity estimate for black hole mergers with numerical relativity simulations
by V. Gayathri, J. Healy, J. Lange, B. O’Brien, M. Szczepańczyk, Imre Bartos, M. Campanelli, S. Klimenko, C. O. Lousto, R. O’Shaughnessy in Nature Astronomy
For the first time, scientists believe they have detected a merger of two black holes with eccentric orbits. According to a paper by researchers from Rochester Institute of Technology’s Center for Computational Relativity and Gravitation and the University of Florida, this can help explain how some of the black hole mergers detected by LIGO Scientific Collaboration and the Virgo Collaboration are much heavier than previously thought possible.
Eccentric orbits are a sign that black holes could be repeatedly gobbling up others during chance encounters in areas densely populated with black holes such as galactic nuclei. The scientists studied the most massive gravitational wave binary observed to date, GW190521, to determine if the merger had eccentric orbits.
“The estimated masses of the black holes are more than 70 times the size of our sun each, placing them well above the estimated maximum mass predicted currently by stellar evolution theory,” said Carlos Lousto, a professor in the School of Mathematical Sciences and a member of the CCRG. “This makes an interesting case to study as a second generation binary black hole system and opens up to new possibilities of formation scenarios of black holes in dense star clusters.”
A team of RIT researchers including Lousto, Research Associate James Healy, Jacob Lange ’20 Ph.D. (astrophysical sciences and technology), Professor and CCRG Director Manuela Campanelli, Associate Professor Richard O’Shaughnessy, and collaborators from the University of Florida formed to give a fresh look at the data to see if the black holes had highly eccentric orbits before they merged. They found the merger is best explained by a high-eccentricity, precessing model. To achieve this, the team performed hundreds of new full numerical simulations in local and national lab supercomputers, taking nearly a year to complete.
“This represents a major advancement in our understanding of how black holes merge,” said Campanelli. “Through our sophisticated supercomputer simulations and the wealth of new data provided by LIGO and Virgo’s rapidly advancing detectors, we are making new discoveries about the universe at astonishing rates.”
The Black Hole Mass Function Across Cosmic Times. I. Stellar Black Holes and Light Seed Distribution
by Alex Sicilia, Andrea Lapi, Lumen Boco, Mario Spera, Ugo N. Di Carlo, Michela Mapelli, Francesco Shankar, David M. Alexander, Alessandro Bressan, Luigi Danese in The Astrophysical Journal
How many black holes are out there in the Universe? This is one of the most relevant and pressing questions in modern astrophysics and cosmology.
The intriguing issue has recently been addressed by the SISSA Ph.D. student Alex Sicilia, supervised by Prof. Andrea Lapi and Dr. Lumen Boco, together with other collaborators from SISSA and from other national and international institutions. In a the paper, the authors have investigated the demographics of stellar mass black holes, which are black holes with masses between a few to some hundred solar masses, that originated at the end of the life of massive stars. According to the new research, a remarkable amount around 1% of the overall ordinary (baryonic) matter of the Universe is locked up in stellar mass black holes. Astonishingly, the researchers have found that the number of black holes within the observable Universe at present time is about 40 x 1018 (i.e., 4 followed by 19 zeros!).
As the authors of the research explain: This important result has been obtained thanks to an original approach which combines the state-of-the-art stellar and binary evolution code SEVN developed by SISSA researcher Dr. Mario Spera to empirical prescriptions for relevant physical properties of galaxies, especially the rate of star formation, the amount of stellar mass and the metallicity of the interstellar medium (which are all important elements to define the number and the masses of stellar black holes). Exploiting these crucial ingredients in a self-consistent approach, thanks to their new computation approach, the researchers have then derived the number of stellar black holes and their mass distribution across the whole history of the Universe.
Alex Sicilia, first author of the study, comments: “The innovative character of this work is in the coupling of a detailed model of stellar and binary evolution with advanced recipes for star formation and metal enrichment in individual galaxies. This is one of the first, and one of the most robust, ab initio computation of the stellar black hole mass function across cosmic history.”
The estimate of the number of black holes in the observable Universe is not the only issue investigated by the scientists in this piece of research. In collaboration with Dr. Ugo Di Carlo and Prof. Michela Mapelli from University of Padova, they have also explored the various formation channels for black holes of different masses, like isolated stars, binary systems and stellar clusters. According to their work, the most massive stellar black holes originate mainly from dynamical events in stellar clusters. Specifically, the researchers have shown that such events are required to explain the mass function of coalescing black holes as estimated from gravitational wave observations by the LIGO/Virgo collaboration.
Lumen Boco, co-author of the paper, comments: “Our work provides a robust theory for the generation of light seeds for (super)massive black holes at high redshift, and can constitute a starting point to investigate the origin of ‘heavy seeds’, that we will pursue in a forthcoming paper.
Prof. Andrea Lapi, Sicilia’s supervisor and coordinator of the Ph.D. in Astrophysics and Cosmology at SISSA, adds: “This research is really multidisciplinary, covering aspects of, and requiring expertise in stellar astrophysics, galaxy formation and evolution, gravitational wave and multi-messenger astrophysics; as such it needs collaborative efforts from various members of the SISSA Astrophysics and Cosmology group, and a strong networking with external collaborators.”
Assessing the role of clay and salts on the origin of MARSIS basal bright reflections
by Elisabetta Mattei, Elena Pettinelli, Sebastian Emanuel Lauro, David E. Stillman, Barbara Cosciotti, Lucia Marinangeli, Anna Chiara Tangari, Francesco Soldovieri, Roberto Orosei, Graziella Caprarelli in Earth and Planetary Science Letters
A Southwest Research Institute scientist measured the properties of ice-brine mixtures as cold as -145 degrees Fahrenheit to help confirm that salty water likely exists between grains of ice or sediment under the ice cap at Mars’ south pole. Laboratory measurements conducted by SwRI geophysicist Dr. David Stillman support oddly bright reflections detected by the MARSIS subsurface sounding radar aboard ESA’s Mars Express orbiter.
With a 130-foot antenna, MARSIS flies over the planet, bouncing radio waves over a selected area and then receiving and analyzing the echoes or reflections. Any near-surface liquid water should send a strong bright signal, whereas the radar signal for ice and rock would be much smaller.
Because conventional models assume the Mars south polar cap experiences temperatures much lower than the melting point of water, many scientists have questioned the presence of liquid water. Clay, hydrated salts and saline ices have been proposed as potential explanations for the source of the bright basal reflections. The Italian-led team investigating the proposed phenomena used previously published data, simulations and new laboratory measurements.
“Lakes of liquid water actually exist beneath glaciers in Arctic and Antarctic regions, so we have Earth analogs for finding liquid water below ice,” said Stillman, a specialist in detecting water in any format — liquid, ice or absorbed — on planetary bodies and co-author of a paper describing these findings. “The exotic salts that we know exist on Mars have amazing ‘antifreeze’ properties allowing brines to remain liquid down to -103 degrees Fahrenheit. We studied these salts in our lab to understand how they would respond to radar.”
Stillman has over a decade of experience measuring the properties of materials at cold temperatures to detect and characterize subsurface ice, unfrozen water and the potential for life throughout the solar system. For this project, Stillman measured the properties of perchlorate brines in an SwRI environmental chamber that produces near-liquid-nitrogen temperatures at Mars-like pressures.
“My Italian colleagues reached out to see if my laboratory experiment data would support the presence of liquid water beneath the Martian ice cap,” Stillman said. “The research showed that we don’t have to have lakes of perchlorate and chloride brines, but that these brines could exist between the grains of ice or sediments and are enough to exhibit a strong dielectric response. This is similar to how seawater saturates grains of sand at the shoreline or how flavoring permeates a slushie, but at -103 degrees Fahrenheit below a mile of ice near the South Pole of Mars.”
The search for water in the cosmos is rooted in searching for potential habitability, because all known life requires water.
“In this case ‘following the water’ has led us to place so cold that life as we know it couldn’t flourish,” Stillman said. “But it’s still interesting, and who knows what evolutionary paths extraterrestrial life may have taken?”
The case for an ocean-bearing Mimas from tidal heating analysis
by Alyssa Rose Rhoden, Matthew E. Walker in Icarus
A Southwest Research Institute scientist set out to prove that the tiny, innermost moon of Saturn was a frozen inert satellite and instead discovered compelling evidence that Mimas has a liquid internal ocean. In the waning days of NASA’s Cassini mission, the spacecraft identified a curious libration, or oscillation, in the moon’s rotation, which often points to a geologically active body able to support an internal ocean.
“If Mimas has an ocean, it represents a new class of small, ‘stealth’ ocean worlds with surfaces that do not betray the ocean’s existence,” said SwRI’s Dr. Alyssa Rhoden, a specialist in the geophysics of icy satellites, particularly those containing oceans, and the evolution of giant planet satellites systems.
One of the most profound discoveries in planetary science over the past 25 years is that worlds with oceans beneath layers of rock and ice are common in our solar system. Such worlds include the icy satellites of the giant planets, such as Europa, Titan and Enceladus, as well as distant planets like Pluto. Worlds like Earth with surface oceans must reside within a narrow range of distances from their stars to maintain the temperatures that support liquid oceans. Interior water ocean worlds (IWOWs), however, are found over a much wider range of distances, greatly expanding the number of habitable worlds likely to exist across the galaxy.
“Because the surface of Mimas is heavily cratered, we thought it was just a frozen block of ice,” Rhoden said. “IWOWs, such as Enceladus and Europa, tend to be fractured and show other signs of geologic activity. Turns out, Mimas’ surface was tricking us, and our new understanding has greatly expanded the definition of a potentially habitable world in our solar system and beyond.”
Tidal processes dissipate orbital and rotational energy as heat in a satellite. To match the interior structure inferred from Mimas’ libration, tidal heating within the moon must be large enough to keep the ocean from freezing out but small enough to maintain a thick icy shell. Using tidal heating models, the team developed numerical methods to create the most plausible explanation for a steady-state ice shell between 14 to 20 miles thick over a liquid ocean.
“Most of the time when we create these models, we have to fine tune them to produce what we observe,” Rhoden said. “This time evidence for an internal ocean just popped out of the most realistic ice shell stability scenarios and observed librations.”
The team also found that the heat flow from the surface was very sensitive to the thickness of the ice shell, something a spacecraft could verify. For instance, the Juno spacecraft is scheduled to fly by Europa and use its microwave radiometer to measure heat flows in this Jovian moon. This data will allow scientists to understand how heat flow affects the icy shells of ocean worlds such as Mimas, which are particularly interesting as NASA’s Europa Clipper approaches its 2024 launch.
“Although our results support a present-day ocean within Mimas, it is challenging to reconcile the moon’s orbital and geologic characteristics with our current understanding of its thermal-orbital evolution,” Rhoden said. “Evaluating Mimas’ status as an ocean moon would benchmark models of its formation and evolution. This would help us better understand Saturn’s rings and mid-sized moons as well as the prevalence of potentially habitable ocean moons, particularly at Uranus. Mimas is a compelling target for continued investigation.”
TESS Giants Transiting Giants II: The hottest Jupiters orbiting evolved stars
by Nicholas Saunders, Samuel K. Grunblatt, Meng Sun, et al in The Astronomical Journal
Three newly-discovered planets have been orbiting dangerously close to stars nearing the end of their lives.
Out of the thousands of extrasolar planets found so far, these three gas giant planets first detected by the NASA TESS (Transiting Exoplanet Survey Satellite) Mission, have some of the shortest-period orbits around subgiant or giant stars. One of the planets, TOI-2337b, will be consumed by its host star in less than 1 million years, sooner than any other currently known planet.
“These discoveries are crucial to understanding a new frontier in exoplanet studies: how planetary systems evolve over time,” explained lead author Samuel Grunblatt, a postdoctoral fellow at the American Museum of Natural History and the Flatiron Institute in New York City. Grunblatt, who earned his PhD from the University of Hawaii Institute for Astronomy (UH IfA), added that “these observations offer new windows into planets nearing the end of their lives, before their host stars swallow them up.”
The researchers estimate that the planets have masses between 0.5 and 1.7 times Jupiter’s mass, and sizes that range from slightly smaller to more than 1.6 times the size of Jupiter. They also span a wide range of densities, from styrofoam-like to three times denser than water, implying a wide variety of origins. These three planets are believed to be just the tip of the iceberg.
“We expect to find tens to hundreds of these evolved transiting planet systems with TESS, providing new details on how planets interact with each other, inflate, and migrate around stars, including those like our Sun,” said Nick Saunders, a graduate student at UH IfA and co-author of the study.
The planets were first found in NASA TESS Mission full-frame image data taken in 2018 and 2019. Grunblatt and his collaborators identified the candidate planets in TESS data, and then used W. M. Keck Observatory’s High-Resolution Echelle Spectrometer (HIRES) on Maunakea, Hawaii to confirm the existence of the three planets.
“The Keck observations of these planetary systems are critical to understanding their origins, helping reveal the fate of solar systems like our own,” said UH IfA Astronomer Daniel Huber, who co-authored the study.
Current models of planet dynamics suggest that planets should spiral in toward their host stars as the stars evolve over time, particularly in the last 10 percent of the star’s lifetime. This process also heats the planets, potentially causing their atmospheres to inflate. However, this stellar evolution will also cause the orbits of planets around the host star to come closer to one another, increasing the likelihood that some of them will collide, or even destabilize the entire planetary system.
The wide variety of planet densities found in the study suggests that these planetary systems have been shaped through chaotic planet-to-planet interactions. This could also have resulted in unpredictable heating rates and timescales for these planets, giving them the wide range in densities we observe today.
Future observations of one of these systems, TOI-4329, with the recently-launched James Webb Space Telescope could reveal evidence for water or carbon dioxide in the planet’s atmosphere. If these molecules are seen, the data would provide constraints on where these planets formed, and what sort of interactions had to occur to produce the planetary orbits we see today.
Continued monitoring of these systems with the NASA TESS telescope will constrain the rate at which these planets are spiraling into their host stars. So far, no clear signal of orbital decay has been observed in any of the systems, but a longer baseline of observations with the TESS Extended Missions will provide much tighter constraints on planet in-spiral than are currently possible, revealing how strongly planetary systems are affected by stellar evolution.
The team hopes that this ‘planetary archeology’ will help us to understand the past, present, and future of planetary systems, moving us one step closer to answering the question: “Are we alone?”
The TESS-Keck Survey. VIII. Confirmation of a Transiting Giant Planet on an Eccentric 261 Day Orbit with the Automated Planet Finder Telescope
by Paul A. Dalba, Stephen R. Kane, Diana Dragomir, et al in The Astronomical Journal
A UC Riverside astronomer and a group of eagle-eyed citizen scientists have discovered a giant gas planet hidden from view by typical stargazing tools.
The planet, TOI-2180 b, has the same diameter as Jupiter, but is nearly three times more massive. Researchers also believe it contains 105 times the mass of Earth in elements heavier than helium and hydrogen. Nothing quite like it exists in our solar system.
“TOI-2180 b is such an exciting planet to have found,” said UCR astronomer Paul Dalba, who helped confirm the planet’s existence. “It hits the trifecta of 1) having a several-hundred-day orbit, 2) being relatively close to Earth (379 lightyears is considered close for an exoplanet), and 3) us being able to see it transit in front of its star. It is very rare for astronomers to discover a planet that checks all three of these boxes.”
Dalba also explained that the planet is special because it takes 261 days to complete a journey around its star, a relatively long time compared to many known gas giants outside our solar system. Its relative proximity to Earth and the brightness of the star it orbits also make it likely astronomers will be able to learn more about it.
In order to locate exoplanets, which orbit stars other than our sun, NASA’s TESS satellite looks at one part of the sky for a month, then moves on. It is searching for dips in brightness that occur when a planet crosses in front of a star.
“The rule of thumb is that we need to see three ‘dips’ or transits before we believe we’ve found a planet,” Dalba said. A single transit event could be caused by a telescope with a jitter, or a star masquerading as a planet. For these reasons, TESS isn’t focused on these single transit events. However, a small group of citizen scientists is. Looking over TESS data, Tom Jacobs, a group member and former U.S. naval officer, saw light dim from the TOI-2180 star, just once. His group alerted Dalba, who specializes in studying planets that take a long time to orbit their stars.
Using the Lick Observatory’s Automated Planet Finder Telescope, Dalba and his colleagues observed the planet’s gravitational tug on the star, which allowed them to calculate the mass of TOI-2180 b and estimate a range of possibilities for its orbit.
Hoping to observe a second transit event, Dalba organized a campaign using 14 different telescopes across three continents in the northern hemisphere. Over the course of 11 days in August 2021, the effort resulted in 20,000 images of the TOI-2180 star, though none of them detected the planet with confidence. However, the campaign did lead the group to estimate that TESS will see the planet transit its star again in February, when they’re planning a follow up study.
The citizen planet hunters’ group takes publicly available data from NASA satellites like TESS and looks for single transit events. While professional astronomers use algorithms to scan a lot of data automatically, the Visual Survey Group uses a program they created to inspect telescope data by eye.
“The effort they put in is really important and impressive, because it’s hard to write code that can identify single transit events reliably,” Dalba said. “This is one area where humans are still beating code.”
Depleted carbon isotope compositions observed at Gale crater, Mars
by Christopher H. House et al. in PNAS
NASA’s Curiosity rover landed on Mars on Aug. 6, 2012, and since then has roamed Gale Crater taking samples and sending the results back home for researchers to interpret. Analysis of carbon isotopes in sediment samples taken from half a dozen exposed locations, including an exposed cliff, leave researchers with three plausible explanations for the carbon’s origin — cosmic dust, ultraviolet degradation of carbon dioxide, or ultraviolet degradation of biologically produced methane.
The researchers note that “All three of these scenarios are unconventional, unlike processes common on Earth.”
Carbon has two stable isotopes, 12 and 13. By looking at the amounts of each in a substance, researchers can determine specifics about the carbon cycle that occurred, even if it happened a very long time ago.
“The amounts of carbon 12 and carbon 13 in our solar system are the amounts that existed at the formation of the solar system,” said Christopher H. House, professor of geosciences, Penn State. “Both exist in everything, but because carbon 12 reacts more quickly than carbon 13, looking at the relative amounts of each in samples can reveal the carbon cycle.”
Curiosity, which is led by NASA’s Jet Propulsion Laboratory in Southern California, has spent the last nine years exploring an area of Gale Crater that has exposed layers of ancient rock. The rover drilled into the surface of these layers and recovered samples from buried sedimentary layers. Curiosity heated the samples in the absence of oxygen to separate any chemicals. Spectrographic analysis of a portion of the reduced carbon produced by this pyrolysis showed a wide range of carbon 12 and carbon 13 amounts depending on where or when the original sample formed. Some carbon was exceptionally depleted in carbon 13 while other carbon samples where enriched.
“The samples extremely depleted in carbon 13 are a little like samples from Australia taken from sediment that was 2.7 billion years old,” said House. “Those samples were caused by biological activity when methane was consumed by ancient microbial mats, but we can’t necessarily say that on Mars because it’s a planet that may have formed out of different materials and processes than Earth.”
To explain the exceptionally depleted samples, the researchers suggest three possibilities — a cosmic dust cloud, ultraviolet radiation breaking down carbon dioxide, or ultraviolet degradation of biologically created methane. According to House, every couple of hundred million years the solar system passes through a galactic molecular cloud.
“It doesn’t deposit a lot of dust,” said House. “It is hard to see any of these deposition events in the Earth record.”
To create a layer that Curiosity could sample, the galactic dust cloud would have first lowered the temperature on a Mars that still contained water and created glaciers. The dust would have deposited on top of the ice and would then need to remain in place once the glacier melted, leaving behind a layer of dirt that included the carbon.
So far, there is limited evidence of past glaciers at Gale Crater on Mars. According to the researchers, “this explanation is plausible, but it requires additional research.”
A second possible explanation for lower amounts of carbon 13 is the ultraviolet conversion of carbon dioxide to organic compounds like formaldehyde.
“There are papers that predict that UV could cause this type of fractionation,” said House. “However, we need more experimental results showing this size fractionation so we can rule in or rule out this explanation.”
The third possible method of producing carbon 13 depleted samples has a biological basis.
On Earth, a strongly carbon 13 depleted signature from a paleosurface would indicate past microbes consumed microbially produced methane. Ancient Mars may have had large plumes of methane being released from the subsurface where methane production would have been energetically favorable. Then, the released methane would either be consumed by surface microbes or react with ultraviolet light and be deposited directly on the surface. However, according to the researchers, there is currently no sedimentary evidence of surface microbes on the past Mars landscape, and so the biological explanation highlighted in the paper relies on ultraviolet light to place the carbon 13 signal onto the ground.
“All three possibilities point to an unusual carbon cycle unlike anything on Earth today,” said House. “But we need more data to figure out which of these is the correct explanation. It would be nice if the rover would detect a large methane plume and measure the carbon isotopes from that, but while there are methane plumes, most are small, and no rover has sampled one large enough for the isotopes to be measured.”
House also notes that finding the remains of microbial mats or evidence of glacial deposits could also clear things up, a bit.
“We are being cautious with our interpretation, which is the best course when studying another world,” said House.
Curiosity is still collecting and analyzing samples and will be returning to the pediment where it found some of the samples in this study in about a month.
“This research accomplished a long-standing goal for Mars exploration,” said House. “To measure different carbon isotopes — one of the most important geology tools — from sediment on another habitable world, and it does so by looking at 9 years of exploration.”
Organic synthesis associated with serpentinization and carbonation on early Mars
by A. Steele et al. . in Science
Organic molecules found in a meteorite that hurtled to Earth from Mars were synthesized during interactions between water and rocks that occurred on the Red Planet about 4 billion years ago, according to new analysis led by Carnegie’s Andrew Steele.
The meteorite, called Allan Hills (ALH) 84001, was discovered in the Antarctic in 1984 and is considered one of the oldest known projectiles to reach Earth from Mars.
“Analyzing the origin of the meteorite’s minerals can serve as a window to reveal both the geochemical processes occurring early in Earth’s history and Mars’ potential for habitability,” explained Steele, who has done extensive research on organic material in Martian meteorites and is a member of both the Perseverance and Curiosity rovers’ science teams.
Organic molecules contain carbon and hydrogen, and sometimes include oxygen, nitrogen, sulfur, and other elements. Organic compounds are commonly associated with life, although they can be created by non-biological processes as well, which are referred to as abiotic organic chemistry.
For years, scientists have debated the origin story for the organic carbon found in the Allan Hills 84001 meteorite, with possibilities including various abiotic process related to volcanic activity, impact events on Mars, or hydrological exposure, as well as potentially the remnants of ancient life forms on Mars or contamination from its crash landing on Earth.
The Steele-led team, which also included Carnegie’s Larry Nittler, Jianhua Wang, Pamela Conrad, Suzy Vitale, and Vincent Riggi as well as researchers from GFZ German Research Centre for Geosciences, Free University of Berlin, NASA Johnson Space Center, NASA Ames Research Center, and Rensselaer Polytechnic Institute, used a variety of sophisticated sample preparation and analysis techniques — including co-located nanoscale imaging, isotopic analysis, and spectroscopy — to reveal the origin of organic molecules in the Allan Hills 84001 meteorite.
They found evidence of water-rock interactions similar to those that happen on Earth. The samples indicate that the Martian rocks experienced two important geochemical processes. One, called serpentinization, occurs when iron- or magnesium-rich igneous rocks chemically interact with circulating water, changing their mineralogy and producing hydrogen in the process. The other, called carbonization, involves interaction between rocks and slightly acidic water containing dissolved carbon dioxide and results in the formation of carbonate minerals.
It is unclear whether these processes were induced by surrounding aqueous conditions simultaneously or sequentially, but the evidence indicates that the interactions between water and rocks did not occur over a prolonged period. What is evident, however, is that the reactions produced organic material from the reduction of carbon dioxide.
These mineralogical features are rare in Martian meteorites, and while carbonation and serpentinization have been shown in orbital surveys of Mars and carbonation has been found in other, less-ancient, Martian meteorites, this is the first instance of these processes occurring in samples from ancient Mars. Organic molecules have been detected by Steele in other Martian meteorites and from his work with the Sample Analysis at Mars (SAM) team on the Curiosity rover, indicating that abiotic synthesis of organic molecules has been a part of Martian geochemistry for much of the planet’s history.
“These kinds of non-biological, geological reactions are responsible for a pool of organic carbon compounds from which life could have evolved and represent a background signal that must be taken into consideration when searching for evidence of past life on Mars,” Steele concluded. “Furthermore, if these reactions happened on ancient Mars, they must have happened on ancient Earth, and could possibly explain the results from Saturn’s moon Enceladus as well. All that is required for this type of organic synthesis is for a brine that contains dissolved carbon dioxide to percolate through igneous rocks. The search for life on Mars is not just an attempt to answer the question ‘are we alone?’ It also relates to early Earth environments and addresses the question of ‘where did we come from?’”
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