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What’s the most important thing you need to live and work on the Moon? Power. For NASA’s upcoming Artemis program, getting power to lunar bases is a top priority. That’s why the agency created its Fission Surface Power Project. The idea is to develop concepts for a small nuclear fission reactor to generate electricity on the lunar surface.

The project just finished its initial phase (which began in 2022), which consisted of three $5 million contracts to commercial partners to develop fission reactor designs. NASA selected Lockheed Martin in Bethesda, MD, Westinghouse of Cranberry, PA, and IX of Houston, TX each for a 12-month Phase 1 award to further develop preliminary designs. Each partner was tasked to offer a design of the reactor and systems for power conversion, heat rejection, and power management and distribution. Of course, the partners needed to provide estimated costs for their systems and development plans. The ultimate goal was to create a system that could support lunar bases for a decade. The designs would also serve as pathways to plan and build similar systems on Mars.

Power systems spell the difference between success and failure in any mission. For the Moon and Mars, it’s the difference between life and death. Nuclear power is the most likely route to service long-term power needs. “A demonstration of a nuclear power source on the Moon is required to show that it is a safe, clean, reliable option,” said Trudy Kortes, program director, Technology Demonstration Missions within NASA’s Space Technology Mission Directorate at NASA Headquarters in Washington. “The lunar night is challenging from a technical perspective, so having a source of power such as this nuclear reactor, which operates independent of the Sun, is an enabling option for long-term exploration and science efforts on the Moon.”

Why Fission Reactors?

Let’s face it—living and working on the Moon presents a lot of challenges. Safe, clean power helps overcome many of the dangers that lunar explorers will face. Solar power provides a dependable source of power to keep things going. But, at least half of the time, solar power grids will be in darkness during the lunar night. That’s not to say solar power won’t be used. But, another power source is important to have. That’s where fission reactors come in handy.

Nuclear fission power plants like these could enable long-term exploration of the Moon for both humans and robotic probes. Credit: NASA

NASA and other agencies could put nuclear reactors in places that spend their time in partial or full shadow. In many cases, in situ reservoirs of ice exist in the same regions. The advantage of nuclear reactors is that they can operate full-time, regardless of whether there’s sunlight or not. That’s a big plus for power needs during the 14-night-long lunar night.

Note that NASA isn’t saying that ONLY nuclear fission generators will be used on the Moon. A combination of solar and nuclear installations will likely supply the electricity needs of habitats and science labs.

Reactor Specs for the Moon and Beyond

In its solicitation for further work on the designs, NASA wanted to see plans for reactors that would last at least a decade without human intervention. This reduces any threats from accidental radiation exposure and allows lunar explorers to focus on their primary science and exploration tasks.

The specs for the reactor design specify that it be under six metric tons and produce 40 kilowatts of power. That is enough to demonstrate the capability of the system and provide power for habitats, grids, and science experiments. If you put the same reactor on Earth in a typical neighborhood, it would be enough to power 33 homes.

The agency designed the requirements to be open and flexible so that each company could feel free to explore new directions when it came to the designs they submitted. “There was a healthy variety of approaches; they were all very unique from each other,” said Lindsay Kaldon, Fission Surface Power project manager at NASA’s Glenn Research Center in Cleveland. “We didn’t give them a lot of requirements on purpose because we wanted them to think outside the box.”

Now with feedback from the commercial partners, NASA begins working on a Phase 2 solicitation for 2025. After that, the agency expects delivery of a system for use on the Moon in the early 2030s. In the distant future, after the systems have gone through their “baptism by fire” on the Moon, NASA will likely redesign a nuclear fission reactor specifically for use on Mars.

For More Information

NASA’s Fission Surface Power Project Energizes Lunar Exploration
NASA Fission Surface Power Project

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Astronomers working with the JWST found a dwarf galaxy they weren’t looking for. It’s about 98 million years away, has no neighbours, and was in the background of an image of other galaxies. This isolated galaxy shows a lack of star-formation activity, which is very unusual for an isolated dwarf.

Most isolated dwarf galaxies form stars, according to a wealth of observations. What’s different about this one?

The JWST’s PEARLS (Prime Extragalactic Areas for Reionization and Lensing Science) observing program is aimed at understanding the epoch of galaxy assembly, active galactic nucleus (AGN) growth, and First Light. As part of its work, it observed a galaxy cluster called CLG1212. The isolated dwarf galaxy, named PEARLSDG, was found serendipitously.

The discovery is in new research published in The Astrophysical Journal Letters. Its title is “PEARLS: A Potentially Isolated Quiescent Dwarf Galaxy with a Tip of the Red Giant Branch Distance of 30 Mpc.” The lead author is Tim Carleton, an Assistant Research Scientist at the Arizona State University.

Dwarf galaxies contain far fewer stars than galaxies like our Milky Way. Nobody’s certain how many stars are in the Milky Way exactly. But well-reasoned estimates point to an upper number of about 400 billion. In contrast, dwarf galaxies like PEARLSDG contain up to about 100 million stars.

Besides its lack of star formation, PEARLSDG is unusual for another reason. The JWST is able to discern individual red giant branch (RGB) stars in the dwarf galaxy because the stars are bright in JWST’s observed wavelengths. It’s almost too far away for the JWST to see the stars, so PEARLSDG is one of the most distant galaxies in which we can see individual stars.

The JWST was able to discern individual stars in the dwarf galaxy, as shown in this image from the research. Image Credit: Carleton et al. 2024

Being able to see individual red giant branch (RGB) stars makes studying the dwarf galaxy much easier. RGB stars have a specific intrinsic brightness, and that means that the astronomers behind the discovery can measure the galaxy’s distance: about 98 million light-years away. They can also measure the stars’ ages, showing that the PEARLSDG stellar population is older. If it were still forming stars, some of the stars would be much younger.

The researchers write that the dwarf galaxy hasn’t formed a star in at least one billion years. Part of the evidence is in the lack of UV energy from the galaxy. Young stars emit powerful UV, yet PEARLSDG displays only low levels of UV radiation. “Consistent with its low level of UV emission and the lack of emission lines in its spectrum, we find a very low sSFR, suggesting that its star formation shut off over 1 Gyr ago,” the researchers explain.

When a galaxy ceases to form stars, it’s called a quiescent galaxy. In a quiescent galaxy, the supply of gas used in star formation has been quenched. It’s usually caused by another neighbouring galaxy that has interacted with the quiescent galaxy to halt star formation. Somehow, the interaction has stripped gas from the quiescent galaxy or disrupted the flow of gas.

But PEARLSDG has no close neighbours.

The JWST’s NIRCam instrument was imaging the regions in the green boxes when it also spotted PEARLSDG, the dwarf galaxy in the cyan box. Image Credit: Carleton et al. 2024

“These types of isolated quiescent dwarf galaxies haven’t really been seen before except for relatively few cases. They are not really expected to exist given our current understanding of galaxy evolution, so the fact that we see this object helps us improve our theories for galaxy formation,” said lead author Carleton. “Generally, dwarf galaxies that are out there by themselves are continuing to form new stars.”

Interactions with other galaxies can cause quenching through tidal stripping. So can other environmental effects like ram pressure stripping and strangulation. But there are other causes, too, though astronomers are still working to understand them. “However, recent observations of large numbers of ultra-diffuse galaxies have prompted the development of internal quenching mechanisms, such as strong feedback,” the researchers state. In strong feedback, powerful energy from the biggest and brightest stars can blow away gas needed for new stars to form.

Despite the fact that PEARLSDG has no close neighbours, the authors are cautious in their conclusions. “Regardless, we cannot completely rule out past interactions with other galaxies that may have affected its formation history,” they write. “However, the recessional velocity and luminosity distance of PEARLSDG are consistent with it being in the Hubble Flow, and there are no visible signatures of tidal interactions.”

The Hubble Flow is what makes galaxies recede from one another as the Universe expands. Some galaxies interact and even merge despite the expansion because other forces have acted on them. But there’s no indication that anything has interacted with the dwarf galaxy that could’ve quenched its star formation.

When galaxies interact with one another, the tidal forces distort their shapes and can create tails and streams of stretched-out gas, dust, and stars. But PEARLSDG shows none of these symptoms. It’s a fairly non-descript, normal-shaped dwarf galaxy.

A pair of interacting galaxies called Arp 273. The larger of the spiral galaxies, known as UGC 1810, has a disk that is distorted into a rose-like shape by the gravitational tidal pull of the companion galaxy below it, known as UGC 1813. Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Discoveries like this make astronomers pause and reconsider their models of galaxy evolution. But it’s likely that the JWST will find more isolated and quiescent dwarf galaxies. As more are observed, things will become clearer, and eventually, there’ll be an explanation.

“More detailed analysis of the star formation history of PEARLSDG and the dynamics of PEARLSDG with respect to its surroundings are needed to further understand its formation history, but this discovery suggests the possibility that many isolated quiescent galaxies are waiting to be identified and that JWST has the tools to do so,” the researchers write.

But for now, it’s just one more mystery in the cosmos.

“This was absolutely against people’s expectations for a dwarf galaxy like this,” Carleton said.

The post The JWST Discovers a Galaxy That Shouldn’t Exist appeared first on Universe Today.

It’s a long way to the nearest star, which means conventional rockets won’t get us there. The fuel requirements would make our ship prohibitively heavy. So an alternative is to travel light. Literally. Rather than carrying your fuel with you, simply attach your tiny starship to a large reflective sail, and shine a powerful laser at it. The impulse of photons would push the starship to a fraction of light speed. Riding a beam of light, a lightsail mission could reach Proxima Centauri in a couple of decades. But while the idea is simple, the engineering challenges are significant, because, across decades and light-years, even the smallest problem can be difficult to solve.

One example of this can be seen in a recent arXiv paper. It looks at the problem of how to balance a lightsail on a laser beam. Although the laser could be aimed directly toward a star, or where it will be in a couple of decades, the lightsail would only follow the beam if it is perfectly balanced. If a sail is slightly tilted relative to the beam, the reflected laser light would give the lightsail a slight transverse push. No matter how small this deviation is, it would grow over time, causing its path to drift ever away from its target. We will never align a lightsail perfectly, so we need some way to correct small deviations.

How a small deviation can send a lightsail off course. Credit: Mackintosh, et al

For traditional rockets, this can be done with internal gyroscopes to stabilize the rocket, and engines that can dynamically adjust their thrust to restore balance. But a gyro system would be too heavy for an interstellar lightsail, and adjustments of the beam would take months or years to reach the lightsail, making quick changes impossible. So the authors suggest using a radiative trick known as the Poynting–Robertson effect.

The effect was first studied in the early 1900s and is caused by the relative motion between an object and a light source. For example, a dust grain orbiting the Sun sees light coming at a slight forward angle due to its motion through sunlight. That little forward component of light can slow down the asteroid ever so slightly. This effect causes dust to drift toward the inner solar system over time.

In this paper, the authors consider a two-dimensional model to see how the Poynting–Robertson effect might be used to keep our lightsail probe on course. To keep things simple, they assumed the light beam to be a simple monochromatic plane wave. Real lasers are more complex, but the assumption is reasonable for a proof of concept. They then showed how a simple two-sail system can use the effects of relative motion to keep the craft in balance. As the sails tilt off course slightly, a restorative force from the beam counters it. Thus proving the concept could work.

However, the authors noticed that over time the effects of relativity come into play. Earlier studies have taken the Doppler effect of relative motion into effect, but this study shows the relativistic version of chromatic aberration would also come into play. The full relativistic effects would need to be accounted for in a realistic design, which would require sophisticated modeling and optics.

So a lightsail still seems like a possible way to reach the stars. We just have to be careful not to make light of the engineering challenges.

Reference: Mackintosh, Rhys, et al. “Poynting-Robertson damping of laser beam driven lightsails.” arXiv preprint arXiv:2401.16924 (2024).

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Trappist-1 is a fascinating exoplanetary system. Seven worlds orbiting a red dwarf star just 40 light-years away. All of the worlds are similar to Earth in mass and size, and 3 or 4 of them are potentially habitable. Imagine exploring a system of life-rich worlds within easy traveling distance of each other. It’s a wonderful dream, but as a new study shows it isn’t likely that life exists in the system. It’s more likely the planets are barren and stripped of their atmospheres.

The Trappist system has gained a lot of attention since its discovery in 2017, because at first blush it seems to be a perfect system for alien life. Plenty of warm terrestrial worlds, similar to our inner solar system. But one question was whether red dwarf stars are suited for habitable worlds. Red dwarfs are much cooler than the Sun, so any habitable world would need to orbit the star very closely. Red dwarfs are also known to have intense solar flares, which can bake nearby planets in X-rays and other dangers. Could life survive these threats over a span of billions of years? If Trappist-1 is typical, the answer seems to be no.

Apparent sizes seen from a Trappist-1 planet. Credit: NASA/Brian Koberlein

This new work looks at the potential atmospheres of the Trappist planets. Observations from JWST have confirmed that the two innermost planets lack any meaningful atmosphere, but that was expected. In our own system, Mercury has no atmosphere. But it has been generally thought that the cooler and more distant worlds of Trappist-1 could maintain atmospheres. So the team looked to computer simulations.

Given observations of Trappist-1 and other red dwarf stars, the authors calculated the amount of high-energy radiation the star likely emits over time. They then simulated the effects of that radiation on the possible early atmospheres of the outer Trappist exoplanets. From that, they modeled the rate of atmospheric evaporation. All planets lose a bit of atmosphere over time, even Earth. The question is how much and how quickly. The team found that for the Trappist worlds, the answer is a lot and fast.

Based on the current radiation levels of Trappist-1, even its outer planets would lose an Earth’s atmosphere worth of gases within a few hundred million years. Planets such as Earth, Mars, and Venus had very thick atmospheres in their youth, so we could assume the Trappist worlds would have as well. But young red dwarfs give off even more high-energy radiation, so atmospheres would evaporate at an even faster rate. Since Trappist-1 is a bit older than our Sun, about 8 billion years old, any atmosphere the Trappist worlds might have had is likely long gone.

So the Trappist-1 system is likely little more than a collection of warm, dry rocks. And this could be true for most other red dwarf systems. That has some pretty serious implications for the possibility of extra-terrestrial life. Red dwarfs make up about 75% of stars in our galaxy, compared to only 8% for Sun-like stars. If red dwarfs strip the atmospheres of their worlds, then most planetary systems are lifeless.

So look around. The vibrant living you see may be much more rare than we thought.

Reference: Van Looveren, Gwenaël, et al. “Airy worlds or barren rocks? On the survivability of secondary atmospheres around the TRAPPIST-1 planets.” arXiv preprint arXiv:2401.16490 (2024).

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In the 1970s, astronomers deduced that the persistent radio source coming from the center of our galaxy was actually a supermassive black hole (SMBH). This black hole, known today as Sagittarius A*, is over 4 million solar masses and is detectable by the radiation it emits in multiple wavelengths. Since then, astronomers have found that SMBHs reside at the center of most massive galaxies, some of which are far more massive than our own! Over time, astronomers observed relationships between the properties of galaxies and the mass of their SMBHs, suggesting that the two co-evolve.

Using the GRAVITY+ instrument at the Very Large Telescope Interferometer (VLTI), a team from the Max Planck Institute for Extraterrestrial Physics (MPE) recently measured the mass of an SMBH in SDSS J092034.17+065718.0. At a distance of about 11 billion light-years from our Solar System, this galaxy existed when the Universe was just two billion years old. To their surprise, they found that the SMBH weighs in at a modest 320 million solar masses, which is significantly under-massive compared to the mass of its host galaxy. These findings could revolutionize our understanding of the relationship between galaxies and the black holes residing at their centers.

The relationship between a galaxy’s properties and its SMBH has been observed many times in the local Universe. To determine if this has always been the norm, astronomers have been eagerly waiting to get a look at galaxies that existed during Cosmic Dawn, the period shortly after the Big Bang when the first galaxies formed. However, it remains extremely difficult (or even impossible) to measure black hole masses for these far-away galaxies using traditional direct methods, even where quasars (“quasi-stellar objects”) are involved.

Illustration of the GRAVITY+ observations of a quasar in the early Universe. © T. Shimizu; background image: NASA/WMAP; quasar illustration: ESO/M. Kornmesser; VLT array: ESO/G. Hüdepohl

This particularly bright class of galaxies is a subset of galaxies with very Active Galactic Nuclei (AGNs), where the centers will temporarily outshine all the stars in the disk. Fortunately, next-generation telescopes and instruments are allowing astronomers to get a look at these early galaxies for the first time. This includes the GRAVITY interferometric instrument aboard the VLTI, which combines light from all four 8-meter (26.25 ft) telescopes of the ESO Very Large Telescope interferometrically, creating a single virtual telescope with a diameter of 130 meters (426.5 ft).

Thanks to recent upgrades, the GRAVITY instrument’s successor (GRAVITY+) is allowing astronomers to precisely study black hole growth at another critical epoch called “Cosmic Noon,” when both black holes and galaxies were rapidly growing. “In 2018, we did the first breakthrough measurements of a quasar’s black hole mass with GRAVITY. This quasar was very nearby, however.” said Taro Shimizu, a staff scientist at the Max Planck Institute for Extraterrestrial Physics, in an MPE press release: “Now, we have pushed all the way out to a redshift of 2.3, corresponding to a lookback time of 11 billion years.”

Thanks to the improved performance enabled by GRAVITY+, astronomers can push the envelope and take images of black holes in the early Universe 40 times sharper than what is possible even with the James Webb Space Telescope (JWST). With the help of the GRAVITY+, the team was able to build on their previous observations and spatially resolve the motion of the gas and dust that make up the accretion disk around the central black hole of SDSS J092034.17+065718.0. This allowed them to obtain a direct measurement of the mass of the central black hole.

This artist’s impression depicts a rapidly spinning supermassive black hole surrounded by an accretion disc. Credit: ESO, ESA/Hubble, M. Kornmesser

At 320 million solar masses, the black hole is actually underweight compared to its host galaxy, about 60 billion solar masses. This suggests that the host galaxy grew faster than the SMBH at its center, which could mean there is a delay between galactic and black hole growth for some galaxies. Said Jinyi Shangguan, an MPE scientist with the research group:

“The likely scenario for the evolution of this galaxy seems to be strong supernova feedback, where these stellar explosions expel gas from the central regions before it can reach the black hole at the galactic center. The black hole can only start to grow rapidly – and to catch up to the galaxy’s growth overall – once the galaxy has become massive enough to retain a gas reservoir in its central regions even against supernova feedback.”

Moving forward, the team plans to conduct follow-up observations of other galaxies at Cosmic Noon and make high-precision measurements of their central black holes. These observations will determine if this mass imbalance is the dominant mode of co-evolution for early galaxies and their SMBHs.

Further Reading: Max Planck Institute for Extraterrestrial Physics

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There’s an old trope in science fiction about someone suddenly getting X-ray vision and looking through solid objects. It turns out to be a physical impossibility with our Mark I eyeballs. However, astronomers have found a way around that challenge that lets us study the Universe with X-ray vision.

It’s called x-ray astronomy and it’s been around for 60 years. It reveals some of the most energetic and violent events and objects in the cosmos. Those include things like bright quasars, supernova explosions, streams of hot gas between galaxies, and hot, young stars.

Recently, astronomers in the eROSITA consortium at the Max Planck Institute for Extraterrestrial Physics announced the latest trove of X-ray data from the eROSITA survey. It covers half the X-ray sky and reveals information about 900,000 distinct X-ray sources. That’s more than all the ones ever detected in X-ray astronomy’s decades of history, including discoveries made with Chandra and other orbiting observatories.

About eROSITA

eROSITA is a soft x-ray imaging telescope aboard the Spectrum-RG satellite. Its first all-sky survey, called eRASS1, took place over 7 months beginning on December 12, 2019. At its most sensitive setting, the telescope detected 170 million X-ray photons. That allowed the cameras to measure their energies and arrival times.

The astronomy team, led by principal investigator Andrea Merloni, put together a first-release catalog of data. They also published more than 50 new science papers based on their findings. After finishing this first survey, the instrument carried out three more scans of the entire sky between June 2020 and February 2022. That huge treasuring of x-ray data will be released shortly. The video below explains more about the mission.

eROSITA’s Treasury of X-ray Sources

X-ray astronomy focuses on hot and energetic objects and events in the Universe. Those would be the cores of galaxies (where supermassive black holes lurk), supernova explosions, newborn stars, and other places where matter gets heated to high temperatures.

This preliminary data eRASS1 data set pinpoints about 710,000 supermassive black holes, 180,000 x-ray emitting stars in the Milky Way, and 12,000 clusters of galaxies. It also covers a small number of other exotic sources like X-ray-emitting binary stars, supernova remnants, pulsars, and other objects.

“These are mind-blowing numbers for X-ray astronomy,” says Andrea Merloni, eROSITA principal investigator and first author of the eROSITA catalog paper. “We’ve detected more sources in 6 months than the big flagship missions XMM-Newton and Chandra have done in nearly 25 years of operation.”

The eROSITA first data release is a rich, “multi-layered” look at the sky at several X-ray energies. Each energy level tells astronomers something about the objects and events emitting the X-rays. And, for each set of images and data, the consortium provides more information. There are lists of source classes, sky positions, energies, and precise arrival times of the photons to the instrument. “We’ve made a huge effort to release high-quality data and software,” added Miriam Ramos-Ceja, who leads the eROSITA Operations team. “We hope this will broaden the base of scientists worldwide working with high-energy data and help push the frontiers of X-ray astronomy.”

Zeroing in on Specific X-ray Objects

eROSITA’s science objectives are to use X-rays as a way to detect the hot intergalactic medium of 50 to 100,000 galaxy clusters and groups. It also looks at hot gas in filaments between them. Those filaments glow in X-rays. The instrument is also tasked with detecting accreting black holes hidden in galaxies. Finally, it studied the physics of galactic X-ray sources (which include pre-main-sequence stars, supernova remnants, and X-ray binaries).

eROSITA X-ray image with the newly discovered filament between two galaxy clusters. The distribution of galaxies (white contours, upper left), as seen from the Two Micron All Sky Survey, follows the structure of the filament. In the SLOW simulation, which is tailored to reproduce the main features of the Local Universe, this individual system with both clusters and the filament spine is reproduced as well.
Credit: Dietl et al. (2024)

At least one of the papers released with the new survey data uses x-ray data to constrain cosmological models using clusters of galaxies. In one release image, we see a newly discovered filament of material. It stretches between one portion of the galaxy cluster Abell 3667 and the nearby cluster Abell 3651. This may help astronomers determine how much matter exists in the so-called “warm-hot intergalactic medium”. It gives insight into the formation of large-scale structures (like galaxy clusters) in the Universe.

This X-ray image shows the full extent of the Virgo Cluster in X-rays as seen by eROSITA. The bright white spot at the center is the central galaxy M87. The hazy white glow around M87 is the very hot gas between galaxies. It extends out more in some directions than others, and isn’t circular. This is evidence that the Virgo Cluster is still in the process of forming. Credit: McCall al. (2024)

The nearby Virgo Cluster of galaxies also shows up in the eRASS1 survey and provides a way to study large-scale filamentary structures. In particular, astronomers want to understand the physical effects operating in the outskirts of these massive galaxy clusters. Using the new survey data, plus other all-sky images, a science team explored the structure of the cluster’s outskirts. That included high-energy emissions around galaxies and groups within the cluster. They also studied a so-called 320-kiloparsec-long “x-ray extension” near the galaxy M49.

eROSITA’s Past Work and Future

eROSITA has enabled a huge leap forward in X-ray astronomy since its launch in June 2019. It began operations in October of that year, providing high-resolution X-ray vision of the cosmos. As it scanned the sky, it glimpsed changes in a distant quasar called SMSS J114447.77-430859.3. Those changes give some clues to the growth of the black hole at the heart of the quasar. It observed changes in the brightness variations at the heart of the quasar, indicating that the black hole swallows some of the material that strays into its event horizon. Other material escapes in the form of powerful winds.

The instrument has also detected a newly forming black hole in the early Universe and traced the existence of hot gas all around our own Milky Way Galaxy. The instrument had its first light on October 22, 2019. Currently, it’s in safe mode and technicians are assessing its health and status.

For More Information

eROSITA
eROSITA Science Papers
The X-ray Sky Opens to the World
Discovery of a >13 Mpc long X-ray filament between two galaxy clusters beyond three times their virial radii
The SRG/eROSITA All-Sky Survey: View of the Virgo Cluster

The post Half the Entire Sky, Seen in X-Rays appeared first on Universe Today.

Astronomers have found a new Super-Earth orbiting an M-dwarf (red dwarf) star about 137 light-years away. The planet is named TOI-715b, and it’s about 1.55 Earth’s radius and is inside the star’s habitable zone. There’s also another planetary candidate in the system. It’s Earth-sized, and if it’s confirmed, it will be the smallest habitable zone planet TESS has discovered so far.

TOI-715 is an average red dwarf. It’s about one-quarter the mass and about one-quarter the radius of our Sun. TOI-715b is close to the star, and its tight orbit takes only 19 days to complete one trip around the dwarf star. Since red dwarfs are much dimmer than the Sun, this puts the Super-Earth in the star’s conservative habitable zone.

New research published in the Monthly Notices of the Royal Astronomical Society presents the discovery. It’s titled “A 1.55 Earth-radius habitable-zone planet hosted by TOI-715, an M4 star near the ecliptic South Pole.” The lead author is Georgina Dransfield, from the School of Physics & Astronomy at the University of Birmingham.

The habitable zone is a rather crude way to identify planets that may have liquid water. Its boundaries are unclear and even contradictory since stellar spectral type, planetary albedo, mass, and even how cloudy its atmosphere is can determine if a planet has liquid water.

The idea of a conservative habitable zone (CHZ) is more helpful. It comes from a 2014 paper by Kopparapu et al. It’s a region around a star where a rocky planet receives between 0.42 and 0.842 as much solar insolation as Earth does. Any rocky planet receiving that much energy is in the CHZ, regardless of distance.

The graphic shows optimistic and conservative habitable zone boundaries around cool, low-mass stars. The numbers indicate the names of known Kepler planet candidates. Yellow represents candidates with less than 1.4 times Earth-radius. Green represents planet candidates between 1.4 and 2 Earth radius. Note: the newly discovered planets are not shown. Credit: Penn State.

Discovering a Super-Earth in a star’s CHZ is always exciting. It fuels our sense of wonder about other planets and the possibility that some may harbour other life. For that reason, they’re more intriguing than planets like Hot Jupiters for instance, which have zero possibility of hosting liquid water or life. Not even the hardiest extremophiles can survive a Hot Jupiter’s wicked environment.

But this discovery is also exciting for a couple of other reasons.

“At long last, the era of JWST has arrived, and with it, the age of detailed exoplanetary atmospheric characterization.”

From “A 1.55 Earth-radius habitable-zone planet hosted by TOI-715, an M4 star near the ecliptic South Pole.”

Now that we’ve discovered thousands of exoplanets, astronomers are seeing trends in the population. One of the things they noticed is a gap in the small planet population between 1.5 and 2 Earth radii. It’s known as the small planet radius gap or the sub-Neptune radius gap (also called the Fulton gap and the photoevaporation valley.) At 1.55 Earth radii, TOI-715b is inside the gap.

A histogram of planets with given radii from a sample of 900 Kepler systems. The decreased occurrence rate between 1.5 and 2.0 Earth radii is apparent. It’s sometimes called the Fulton Gap because it comes from Fulton et al. 2017. Image Credit: Fulton et al. 2017.

It’s extremely unlikely that no planets form in this radius gap. Planets must start out larger and lose mass to end up in the gap. So, the Fulton Gap tells us something about how some planets lose mass. Astronomers think that planets in the gap start out larger, but their stars strip away some of their mass by photoevaporation, shrinking them. That’s why it’s sometimes called the photoevaporation valley. There’s a lot of uncertainty around the valley and photoevaporation, and astronomers want to study planets in the valley to see what they can learn.

“The importance of the radius valley lies in its potential to teach us about planetary formation and post-formation evolution, and hence, planets inside this gap are crucial in furthering our understanding of the factors that sculpt it,” the authors explain.

There’s some uncertainty if this radius gap exists around M-dwarfs or not. It’s possible that M-dwarfs have a density gap rather than a radius gap. “A recent study by Luque & Pallé (2022), however, indicates that M-dwarf planets may have a density gap rather than a radius gap separating two populations of small planets (rocky and water worlds),” the authors write.

Whether it’s a radius gap or a density gap, TOI-715b should have something to tell us about exoplanets, photoevaporation, and the nature of exoplanet distribution around red dwarfs. But to discover what it has to tell us requires further, detailed observations. That’s the second reason why this Super-Earth is so intriguing.

Ever since we started finding exoplanets, scientists have looked forward to the day when the James Webb Space Telescope is operational. “At long last, the era of JWST has arrived, and with it, the age of detailed exoplanetary atmospheric characterization,” the authors write in their paper. The JWST has the ability to observe the spectra of exoplanet atmospheres and determine their constituents. But even though the JWST is enormously powerful, some targets present better opportunities for transmission spectroscopy than others.

The JWST hasn’t studied TOI-715b yet, but it can measure an exoplanet’s transit spectrum and its eclipse spectrum, as shown in this spectrum of the exoplanet WASP-80b. During a transit, the planet passes in front of the star, and in a transit spectrum, the presence of molecules makes the planet’s atmosphere block more light at certain colours, causing a deeper dimming at those wavelengths. During an eclipse, the planet passes behind the star, and in this eclipse spectrum, molecules absorb some of the planet’s emitted light at specific colours, leading to a smaller dip in brightness during the eclipse compared to a transit. Image Credit: BAERI/NASA/Taylor Bell.

TOI-715b is a prime target because it’s close to its star. Since TOI-715 is a small red dwarf, and the planet orbits it every 19 days, the exoplanet’s transits in front of its star are deeper and more frequent. That means the JWST doesn’t need much time to observe the planet’s atmosphere, making it an efficient use of the space telescope’s time. “In the context of atmospheric characterization by transmission spectroscopy, bright, nearby M dwarfs are ideal planetary hosts as small temperate planets will transit frequently, enabling high signal-to-noise detections of atmospheric features with fewer hours of telescope time,” the authors explain.

This figure from the study shows the conservative habitable zone in blue. The y-axis shows the Transmission Spectroscopy Metric, a measure of how amenable a planet’s atmosphere is to the JWST spectroscopic measurements. The x-axis shows stellar insolation. TOI-715b is shown in two instances: as a rocky world and as a water world. If it’s a water world, it’s more accessible to effective spectroscopy by the JWST. TOI-715’s other planet candidate is shown in green. Other interesting exoplanets are also shown, including the TRAPPIST-1 planets in yellow. Image Credit: Dransfield et al. 2024.

Can this Super-Earth be habitable? Lacking the JWST’s spectroscopy, we’re reduced to speculating. It’s in the conservative habitable zone, but that doesn’t get us very far. Still, there are some hopeful signs.

TOI-715 is a little older than our Sun at about 6.6 billion years old. The star shows a “low degree of magnetic activity,” according to the authors. That’s probably why the star shows an absence of flaring in the TESS light curves compared to younger M-dwarfs. Red dwarfs are known to exhibit extremely powerful flaring that can sterilize planets. They can also strip away atmospheres, which could be responsible for the exoplanet photoevaporation valley.

This artist’s illustration shows a red dwarf star emitting a powerful flare. Red dwarf flaring can limit the habitability of planets in their habitable zones. Credits: NASA’s Goddard Space Flight Center

Another planet may be orbiting TOI-715. It’s currently only a candidate named TIC 271971130.02, but if confirmed, it will be the smallest habitable zone planet TESS has ever found. But follow-up observations are needed to confirm it.

The TOI-715 system is a compelling target for further study. TOI-715b is waiting its turn, but eventually, the JWST will examine its atmosphere. If those results support habitability, astronomers’ excitement will only grow. At the same time, we may learn more about the radius or density gap, an obstacle to a more thorough understanding of exoplanets.

Add in the fact that the star may host another habitable zone planet, the smallest one found yet by TESS, and the TOI-715 system becomes even more important.

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When we look up at the sky on a particularly dark night, there is a sense of timelessness. We might see the flash of a meteor, and occasionally a comet is visible to the naked eye, but the cold and distant stars are unchanging. Or so it seems. There can also be a sense of calm, that despite all the uncertainty of the world, the stars will always watch over us. So it’s hard to imagine that light years away there could be a lurking event that poses an existential threat to humanity. That threat is extremely tiny, but not zero, and it is the focus of a recent paper published in The Astrophysical Journal.

The study focuses on kilonovae, which can occur when either two neutron stars collide, or a neutron star collides with a stellar-mass black hole. Kilonovae are similar to supernovae, but much more intense. In the paper, the authors look at a particular kilonova known as GW170817. It was detected by the LIGO and Virgo gravitational wave observatories in 2017, and seen as a gamma-ray burst by the Fermi and INTEGRAL space telescopes. Since we have both optical and gravitational observations, the energy of the kilonova can be calculated quite well.

The team took this data and combined it with computer simulations on kilonovae. They wanted to estimate the minimum safe distance of a kilonova. In other words, how close to us could one go off and still be a harmless light show? What they found was that there are several safe distances, depending on which aspect of the supernova poses a threat.

Diagrams of emissions from a binary neutron star merger. Credit: Perkins, et al

One threat would be the X-ray afterglow. When neutron stars collide, a jet of high-energy gamma rays can stream from their common polar region. These jets collide with interstellar gas and create an afterglow of intense X-rays. The intensity of this glow could ionize Earth’s atmosphere, leaving us exposed to things like solar flares and ultraviolet radiation. But only if the kilonova occurred within about 16 light-years of Earth. The gamma rays themselves could pose a similar threat, but only to within about 13 light-years.

But as the team found, the greater threat wouldn’t reach us at the speed of light. After the explosion, a shockwave from the collision would expand away from the kilonova over the span of about a thousand years. When the shockwave collides with interstellar gas and dust, it creates intense cosmic rays. If such a stream of cosmic rays reached us it could vaporize our atmosphere, killing almost all life on Earth. But this would only pose a threat to a distance of about 40 light-years.

GW170817 occurred about 130 million light-years away, so it poses absolutely no threat to us. Even if one were to occur in our stellar neighborhood, it would likely be too distant to pose any harm. As far as we know, there are no binary neutron stars within 40 light-years that will merge any time soon. So there is nothing for us to worry about. Mostly what this study shows is that throughout the cosmos kilonovae can pose a threat to life from time to time, but that threat is not large enough to wipe out a large fraction of worlds. We can face cosmic dangers, but thankfully a kilonova isn’t one of them.

Reference: Perkins, Haille ML, et al. “Could a Kilonova Kill: A Threat Assessment.” The Astrophysical Journal 961.2 (2024): 170.

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Swedish astronaut Marcus Wandt took control of a series of robots in Germany while on board the International Space Station, zipping around the Earth at 28,000 kilometers per hour (17,500 mph.) Researchers want to understand how time delays can affect the remote control of robots from an orbiting platform. Future astronauts could control rovers on the Moon’s or Mars’s surface from a spacecraft in orbit. Until now, only wheeled rovers have been part of the tests, but now they have added a dog-like robot called Bert.

This robot research session, called ‘Surface Avatar’ follows initial experiments carried out in July 2023. Wandt operated the robots from a control station in the space station’s Columbus module, commanding three different robots at the German Space Agency’s (DLR) Robotics and Mechatronics Center in Oberpfaffenhofen, Germany. The goal is to develop innovative technologies that will allow humans to control several robots with precision, and have them act semi- or fully autonomously and even have different robots perform a task together.

As part of the ‘Surface Avatar’ experiment, Swedish ESA astronaut Marcus Wandt commanded various robotic systems from the International Space Station (ISS). Credit: ESA/NASA

“Future stations on the Moon and Mars, including astronaut habitats, will be built and maintained by robots operating under the guidance of astronauts,” said Alin Albu-Schäffer, Director of the DLR Institute of Robotics and Mechatronics, in a DLR article. “Our latest control and AI algorithms enable a single astronaut to command an entire team of different robots. Our DLR-ESA team is a world leader when it comes to this technology.”

The remote operation of the dog-like robot Bert was marked the first time a non-wheel-driven robot was controlled remotely from space by astronauts. Previously, DLR’s humanoid service robot Rollin’ Justin and ESA’s Interact Rover have been teleoperated from space.

During the session, Wandt, who is part of the private Axiom Mission 3 (Ax-3), was able to command Bert to utilize several types of gaits and, because of his leg-based locomotion, Bert was able to explore rough terrain, including small caves — areas that the rolling robots cannot reach. At one point, Wandt allowed Bert to explore the lab’s surroundings independently and monitor the terrain with his camera eyes. Meanwhile, Wandt operated Rollin’ Justin and the Interact Rover.

The ‘Surface Avatar’ series of telerobotics experiments is aimed in particular at the further development of collaborative robots to support astronauts. The project is being led by the DLR Institute of Robotics and Mechatronics, in collaboration with the European Space Agency (ESA) and the German Space Operations Center. Credit: © DLR.

The time delay between the ISS and Earth is usually less than one second.

“That’s because my radio call comes from ISS first to White Sands in the USA,” explained German Space Agency astronaut Matthias Maurer, in a video from DLR. “From there it goes to Houston at NASA. From there it will be forwarded to Munich where our control center is in Oberpfaffenhofen.”

Maurer added that the delay experienced is like what sometimes happens on a Skype call, which occasionally has delays in communications. And of course, the round-trip delay time might be close to 2 seconds, which is deficiently noticeable, especially during conversations.

DLR said that future operations of robots and humans working together must be well planned out in order for them to work as a team. When building a habitat, for example, combining the different skills of several robots is very helpful.

Successful collaboration between two intelligent robots: ESA’s Interact Rover and DLR’s Rollin’ Justin robot jointly installed a short pipe that reproduces a scientific measuring device. The task was coordinated by ESA astronaut Marcus Wandt, who was in control of the robot team in DLR’s Mars laboratory in Oberpfaffenhofen from on board the ISS. Credit: DLR.

Wandt also tested out this concept and for the first time two robots worked together to accomplish a task: Rollin’ Justin and the Interact Rover jointly installed a short pipe representing a scientific measuring device. Under the command of Wandt, Rollin’ Justin used his dexterous hands to safely grasp the pipe and carefully guide it to the measuring point. Wandt then used the Interact rover’s remote control to install the pipe held in position by Justin.

Robots have also been used in space on board the ISS. Robonaut is a joint DARPA–NASA project that created a humanoid torso robot to test out robotics in space. Additionally, three free-flying robots on the space station, known as Astrobees, support multiple demonstrations of technology for various types of robotic assistance on space exploration missions and on Earth.

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After a few days of wakefulness, Japan’s SLIM moon lander has gone dormant once more at the start of a 14-day-long lunar night. The upended robot sent back a stream of data and imagery while its solar cells were in position to soak up sunlight, and its handlers hope they can get SLIM to wake up again and resume its work after lunar sunrise in mid-February.

The car-sized robot accomplished its primary mission on Jan. 20 (Japan time) when it landed within 100 meters of its target point near Shioli Crater. SLIM — which is an acronym standing for “Smart Lander for Investigating Moon” — was designed to demonstrate a precision landing technique that Japan hopes to use for future missions to the moon and Mars.

Unfortunately, the lander ended up in an upside-down position, with its solar cells pointing off to the side. Mission managers were able to get some data and pictures back — including a photo captured by a mini-robot that documented the lander’s predicament. But within hours, the lander’s batteries ran down to the point that SLIM had to go into hibernation. The mission team could only hope that as the sun moved westward in the lunar sky, enough light would eventually hit the panels to allow for a reawakening.

That’s exactly what happened on Jan. 28: The Japan Aerospace Exploration Agency, a.k.a. JAXA, re-established contact with the charged-up SLIM and commanded the lander to transmit a set of multispectral images showing the area around the landing site — including a variety of rocks named after canine breeds, such as Bulldog, Toy Poodle and Aki Inu.

??????????????????SLIM???????????????MBC????10??????????????
??https://t.co/VtNFaNHqOe#JAXA #SLIM #???
?????????JAXA???????????? pic.twitter.com/RgArA9kSMX

— ISAS?JAXA???????? (@ISAS_JAXA) February 1, 2024 This Japanese-language posting shows a variety of rocks around the lander, plus a closeup focusing on a rock that was named Aki Inu.

Communication with SLIM was successfully established last night, and operations resumed! Science observations were immediately started with the MBC, and we obtained first light for the 10-band observation. This figure shows the “toy poodle” observed in the multi-band observation. pic.twitter.com/WYD4NlYDaG

— ????????SLIM (@SLIM_JAXA) January 29, 2024

SLIM’s recent science-gathering session was limited to just a few days due to the moon’s day-night cycle. By the time the lander’s solar cells soaked up enough sunlight, it was the equivalent of late afternoon on the moon. Sunset came on Feb. 1, and once again, SLIM went into hibernation.

“We sent a command to switch on SLIM’s communicator again just in case, but with no response, we confirmed SLIM had entered a dormant state,” the mission team at the Japan Aerospace Exploration Agency said in a posting on X / Twitter.

The final image sent back by the lander shows a dark stretch in the foreground, with the sun’s dying rays reflecting off rocks and off the heights of a ridge rising in the background.

Temperatures were expected to fall to somewhere around 200 degrees below zero Fahrenheit (-130 degrees Celsius) during the lunar night. JAXA initially had planned to let the lander go dead when the sun went down — but in light of the unlucky lander’s recent resilience, those plans could change.

“Although SLIM was not designed for the harsh lunar nights, we plan to try to operate again from mid-February, when the sun will shine again on SLIM’s solar cells,” mission managers said.

Last image from #SLIM (JAXA, 2024.01.31) – The world on the moon alternates between 14 days of day and 14 days of night. This photo was taken of the SLIM landing site just before sunset. Compared to the photo taken immediately after landing, the area that is darkened by the… pic.twitter.com/q5OcA8clEE

— AMSAT-DL (@amsatdl) January 31, 2024

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The Vera Rubin Observatory (VRO) is different than other large telescopes, and that difference makes it more vulnerable to space junk. Other telescopes, like the Giant Magellan Telescope and the European Extremely Large Telescope, focus on distant objects. But the VRO’s job is to repeatedly image the entire available night sky for ten years, spotting transients and variable objects.

All that space junk can look like transient events, impairing the VRO’s vision and polluting its results.

In a new research note awaiting publication, Harvard physicist/astronomer Avi Loeb points out how space junk will affect the VRO’s work. The paper is “Flares from Space Debris in LSST Images.” LSST is the Legacy Survey of Space and Time, the VRO’s primary observing effort.

The problem stems from space junk and also the VRO’s extreme sensitivity, a critical part of its success. “Owing to the exceptional sensitivity of the Vera C. Rubin Observatory, we predict that its upcoming LSST images will be contaminated by numerous flares from centimetre-scale space debris in Low Earth Orbits (LEO),” Loeb writes. “Millisecond-duration flares from these LEO objects are expected to produce detectable image streaks of a few arcseconds with AB magnitudes brighter than 14.”

This NASA video is a representation of space junk orbiting Earth. The debris is obviously not scaled to Earth, but it shows where the greatest orbital debris populations are. Credit: NASA.

Our space junk problem is getting worse, as everyone knows. The ESA says that as of December 6th, 2023, there are 130 million objects in the size range of 0.1-1 cm orbiting Earth. There are also one million objects between 1-10 cm and 36,500 objects larger than 10 cm. With so many launches, the problem is getting worse. Space is a burgeoning economy, and a certain amount of junk goes with it.

Not all of those objects are in the critical Low-Earth Orbit region, but a large subset of them are. According to Loeb, this population of debris has implications for the VRO. “In this Note, we examine the implications of this LEO debris for the upcoming Legacy Survey of Space & Time (LSST) of the Vera C. Rubin Observatory in Chile,” Loeb writes.

When it comes to the VRO’s images, it’s not really the size of the debris that matters. An object’s albedo is the real problem. Albedo can scale with size, but not always.

There’s no way to measure the individual albedos of pieces of space junk, but in this work, Loeb calculates albedo by combining an object’s radius and distance with one of its sides illuminated by the Sun. That yields the fraction of light that it will reflect.

We already know how space junk can reflect light because we can see it with the Zwicky Transient Facility. It’s similar to the VRO in that it detects transient light sources. “Data from the Zwicky Transient Facility (ZTF) shows that the sunlight glints from known LEO satellites generate flashes of duration 10?3±0.5 s.” That’s an extremely brief flash.

But the VRO and its LSST will visit each patch of the sky for 30 seconds and take back-to-back 15-second exposures. The problem is that debris is moving, and rather than just a flash, it creates a streak. “The light from the flares is therefore expected to spread across no more than a few arcseconds, independently of the LSST exposure time which is 4 orders of magnitude longer,” Loeb writes.

What does that mean for the VRO?

It’s not good. According to Loeb, the number of objects that can create problematic streaks “exceeds by an order of magnitude” the number of large satellites orbiting Earth. USA’s Space Surveillance Network regularly tracks satellites and has built a catalogue of orbiting objects that could help the VRO manage the problem. But as Loeb points out, “Out of the entire debris population, only 3.515 × 104 (351,500) objects are regularly tracked and catalogued by Space Surveillance Networks.”

This infographic shows the populations of satellites in different orbits and how urgent it is to clean these orbits. Note the LEO “needs urgent protection,” according to the maker. While it’s primarily about satellites, it drives the space debris problem point home. Image Credit: By Pablo Carlos Budassi – Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=140585562

Streaks of light in images are only part of the problem. There’s the more generalized problem of the combined light from all satellites and debris. Other researchers have examined the problem and its effects on ground-based astronomy. A March 2023 paper in Nature Astronomy showed that by 2030, reflected light from space junk and functioning satellites will increase the diffuse background brightness for the VRO by 7.5%. That means the VRO’s LSST will be 7.5% less efficient. That’ll add over $20 million US to the cost of the 10-year-long LSST.

Satellites and their predictable orbits mean they should be easier to deal with. In fact, the LSST team has a plan to deal with satellites. They propose an updated scheduler that can mitigate the problem. “Overall, sacrificing 10% of LSST observing time to avoid satellites reduces the fraction of LSST visits with streaks by a factor of 2,” the authors of a paper in The Astrophysical Journal Letters write.

But junk is far more abundant. Without a solution, will LSST images be littered with noisy streaks?

It seems irrational to download the responsibility for space debris to the people trying to see the sky through it. Any long-term solution has to include two things: the cleaning up of Low Earth Orbit and an international agreement to stop polluting it even further.

The ESA is coming to terms with the space debris problem. “130 million pieces of space debris larger than a millimetre orbit Earth, threatening satellites now and in the future,” the ESA wrote when announcing their Zero Debris Charter. “Once a week, a satellite or rocket body reenters uncontrolled through our atmosphere. Behaviours in space have to change.” While the Charter is primarily aimed at reducing the risk of collisions, it will benefit ground-based astronomy.

NASA is seeking solutions, too. Their Detect, Track, and Remediate: The Challenge of Small Space Debris competition is reaching out to people around the globe for innovative solutions to the problem.

Those are great initiatives, but the VRO is scheduled to see its first light in early January 2025. A solution to the problem of satellites and satellite constellations in space is likely within reach. But debris is a much thornier problem.

“However, the above numbers suggest that image contamination by untracked space debris might pose a
bigger challenge,” Loeb concludes.

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On December 5th, 2020, Japan’s Hayabusa2 mission successfully returned samples it had collected from the Near-Earth Asteroid (NEA) 162173 Ryugu home. Since asteroids are basically leftover material from the formation of the Solar System, analysis of these samples will provide insight into what conditions were like back then. In particular, scientists are interested in determining how organic molecules were delivered throughout the Solar System shortly after its formation (ca. 4.6 billion years ago), possibly offering clues as to how (and where) life emerged.

The samples have already provided a wealth of information, including more than 20 amino acids, vitamin B3 (niacine), and interstellar dust. According to a recent study by a team of Earth scientists from Tohoku University, the Ryugu samples also showed evidence of micrometeoroid impacts that left patches of melted glass and minerals. According to their findings, these micrometeoroids likely came from other comets and contained carbonaceous materials similar to primitive organic matter typically found in ancient cometary dust.

The team was led by Megumi Matsumoto, an assistant professor from the Earth Science Department at Tohoku University’s Graduate School of Science. He was joined by researchers from the Division of Earth and Planetary Sciences at Kyoto University, the CAS Center for Excellence in Deep Earth Science, the Institute of Space and Astronautical Science (ISAS), the Japan Synchrotron Radiation Research Institute (JASRI), the Japan Aerospace Exploration Agency (JAXA), and NASA’s Johnson Space Center. The details of their findings were presented in a paper that recently appeared in the journal Science Advances.

An artist’s conception shows Hayabusa 2’s sample return capsule making its atmospheric re-entry as its mothership flies above. Credit: JAXA Illustration

Like the Moon and other airless bodies, Ryugu has no protective atmosphere and does not experience weathering or erosion. This ensures that craters caused by past impacts on its surface (which is directly exposed to space) are carefully preserved despite the passage of eons. These impacts generate intense heat that leaves behind melted patches of glass (aka. “melt splashes”), which quickly solidify in the vacuum of space. These impacts cause changes to the composition of the asteroid’s surface materials, revealing information about the history of impacts.

After analyzing the Ryugu samples, Matsumoto and her colleagues found melt splashes ranging in size from 5 to 20 micrometers. Their composition suggests they came from cometary sources that impacted Ryugu while it was in a near-Earth orbit. “Our 3D CT imaging and chemical analyses showed that the melt splashes consist mainly of silicate glasses with voids and small inclusions of spherical iron sulfides,” said Matsumoto in a recent Tohoku University news release. “The chemical compositions of the melt splashes suggest that Ryugu’s hydrous silicates mixed with cometary dust.”

Their analysis revealed small carbonaceous materials with a spongy texture indicative of nano-pores, small voids caused by the release of water vapor from hydrous silicates. This vapor was subsequently captured in the melt splashes, which also contained silicate glasses rich in magnesium and iron (Mg-Fe) and iron-nickel sulfides. The carbonaceous materials are similar in texture to primitive organic matter observed in cometary dust but differ in composition – lacking nitrogen and oxygen. Said Matsumoto:

“We propose that the carbonaceous materials formed from cometary organic matter via the evaporation of volatiles, such as nitrogen and oxygen, during the impact-induced heating. This suggests that cometary matter was transported to the near-Earth region from the outer solar system. This organic matter might be the small seeds of life once delivered from space to Earth.”

The carbonaceous material found in the melt splash shows a spongy texture and contains small iron sulfide inclusions. ©Megumi Matsumoto et al.

Looking ahead, the team hopes to examine more Ryugu samples that will provide further insights into how primitive organic materials were delivered to Earth billions of years ago. Similarly, scientists at NASA’s Johnson Space Center recently completed the careful process of removing the samples collected by the OSIRIS-REx mission from their sample container. Analysis of these samples will reveal the composition and history of asteroid Bennu, another NEA that will provide vital information on how our Solar System evolved.

Further Reading: Tohoku University, Science Advances

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Supernovae are relatively rare. It might not seem like it, but that’s because they’re so bright we can see them in other galaxies a great distance away. In fact, in 2022, astronomers spotted a supernova over 10 billion light-years away.

Any time astronomers spot a supernova, it’s an opportunity to learn more about these rare, cataclysmic explosions. It’s especially valuable if astronomers can get a good look at the progenitor star before it explodes.

We know what types of stars explode as core-collapse supernovae: massive ones. But we don’t know which star will explode when, so we don’t know where to look to see the progenitor. The authors of new research put this succinctly when they write, “Obtaining spectroscopic observations of the progenitors of core-collapse supernovae is often unfeasible due to an inherent lack of knowledge as to which stars will go supernova and when they will explode.”

That quote comes from a new research letter titled “Spectroscopic observations of progenitor activity 100 days before a Type Ibn supernova.” The letter has been submitted to the journal Astronomy and Astrophysics and is currently in pre-press. The lead author is Seán Brennan from the Department of Astronomy at Stockholm University.

Astronomers keep learning more about supernovae progenitors. They’re finding that supernova progenitors can exhibit powerful outbursts in the weeks, months, or even years before they explode. Astronomers keep getting better and better tools to spot these outbursts, and sometimes they get lucky.

In April of 2023, a massive star exploded in NGC 4388, a spiral galaxy about 57 million light-years away. The Zwicky Transient Facility (ZTF) spotted it, and the supernova is called SN 2023fyq. SN 2023fyq is a rare type of supernova called a Type Ibn. They show a lack of hydrogen lines and narrow He I emission lines in their spectra. Astronomers think that these characteristics come from the SN interacting with hydrogen-poor, helium-rich circumstellar material (CSM.)

Astronomers only know of a few of these types of SN, so their progenitors are poorly understood. Prior to its explosion, the ZTF also spotted the precursor activity, providing a window into these mysterious progenitors.

This figure shows the supernova and its location in NGC 3288. Image Credit: Brennan et al. 2024

“This Letter presents spectral and photometric observations of the progenitor of a Type Ibn SN several months before core-collapse, as well as SN 2023fyq itself,” the researchers write. The observations come from multiple telescopes and observatories, including the Keck 10m telescope, the Palomar 200-inch telescope, and the Gemini North 8m telescope.

The researchers found that the progenitor’s luminosity increased exponentially during the 150 days leading up to the explosion. They also found that the radius of the photosphere remained almost constant during the same time. The pre-supernova spectra also “reveal a complex evolving He I profile.”

This chart from the study shows the spectral observations of SN 2023fyq and its progenitor. The progenitor’s observations are on the top, and the SN’s observations are on the bottom. Each line represents a different set of observations, with their times written at their ends. The red line shows observations of SN 2010al, a Type Ibn SN that matches well with SN 2023fyz. He I areas are labelled because the researchers pointed out that there was a complex, evolving He I profile. Image Credit: Brennan et al. 2024

The He I profile could be a clue to some of the progenitor star’s activity. There are similar He I emissions in both the progenitor and the SN. “This would mean that the asymmetric material responsible for this emission was not destroyed in the SN explosion,” the authors explain. “SN ejecta interacting with asymmetric circumstellar material (CSM) has been used to explain irregular emission line profiles.” We’re getting deep into the weeds here, but it’s significant. “… SN 2023fyq provides the first clear spectroscopic evidence of asymmetric structure prior to core-collapse.”

It’s possible that some of the features in the spectroscopy are caused by circumstellar material (CSM). “Some mechanisms cause the progenitor to be surrounded by a dense CSM,” the authors explain, “and may lead to shock dissipation and emission of radiation in the optically thick CSM.” In that case, diffusion could explain the light curve’s general rise. “This also explains the roughly constant radius and the slowly rising effective temperature,” they write.

“These observations of SN 2023fyq and the final moments of the progenitor highlight that the progenitors to CCSNe can undergo some extreme instabilities shortly before their final demise,” the authors write.

It shouldn’t surprise anyone that a progenitor exhibited some extreme instabilities before exploding as a supernova. It would be very strange if a massive star suddenly exploded with no lead-up. Only massive stars explode as supernovae, and it happens when the star’s outward fusion pressure is insufficient to counteract the star’s own gravity. The star collapses in on itself and explodes. This is a cataclysmic event, and there are bound to be shock waves travelling through the star, as well as other interactions. There are bound to be “extreme instabilities,” as the authors call them.

But what exactly does this tell us?

Artist view of a supernova explosion. Credit: NASA

This is just a research letter, and the authors are presenting their results to the astronomical community. They can show the unusual activity evident in spectroscopic observations, but they can’t tell us exactly what it means yet. But it does show that we’re able to spot supernova progenitors, a huge step in understanding core-collapse supernovae.

“Progenitor analysis typically occurs after the star has been destroyed by searching through archival images and measuring the photometric properties of the assumed progenitor,” the researchers write in their letter. “Although this area of transient astronomy is in its infancy, the repercussions of detecting precursor activity are immense, highlighting that the progenitor is not in an equilibrium state and may
not be represented well by standard stellar evolutionary models.”

We’re looking at an SN progenitor when we look at Betelgeuse; astronomers just don’t know how long it’ll be until the star explodes. But it appears to have belched plasma that created a dust cloud that briefly dimmed the star a couple of years ago. Is that behaviour indicative of how other progenitors behave?

Astronomers need to observe more supernova progenitors of different types before they can answer their questions. Once they have more data, they’ll build models of how supernova progenitors behave leading up to the explosion. Then, they can observe even more SN and test that data against their models. Then, they’ll improve their models some more.

Eventually, they’ll have answers.

The post Giant Star Seen 150 Days Before it Exploded as a Supernova appeared first on Universe Today.

Although the exact nature of dark matter continues to elude astronomers, we have gained some understanding of its general physical properties. We know how it clusters around galaxies, how it makes up much of the matter in the Universe, and even how it can interact with itself. Now a new study looks at just how fast dark matter can move.

The study focuses on an effect known as dynamical friction. The term is a bit of a misnomer since it isn’t the kind of friction you see between two objects sliding against each other. A better term for the effect might be gravitational drag. It was first studied by Subrahmanyan Chandrasekhar in 1943, and it’s caused by the gravitational interactions of a diffuse body.

Imagine a massive star moving through a cluster of red dwarf stars. Even though none of the stars are likely to collide, the gravitational interactions between them will affect stellar motions. The massive star will slow down as it leaves the cluster thanks to the gravitational tug of the red dwarf stars. On the other hand, the red dwarf stars will speed up a bit as they are dragged slightly toward the massive star. If you track the change in speed of the stars in the cluster, you can determine how fast the cluster was moving before the collision.

The galactic effects of dynamical friction. Credit: Kipper, et al

The same effect can occur between matter and dark matter. The presence of dark matter affects the motion of stars in the galaxy, and thanks to dynamical friction this distorts the shape of the galaxy. By mapping how the galaxy is distorted the team can calculate the motion of dark matter near the galaxy. So the team focused on finding distorted galaxies that aren’t part of a dense galactic cluster. Since the galaxies are fairly isolated, the distortion must occur because of dark matter.

The authors then compared the shape of these distorted galaxies to N-body simulations to map the motion of dark matter. One of the concerns they had was that the uncertainty in the data would be too large to make any meaningful constraints on dark matter. The team showed that for available samples, the data scatter is only about 10%. This means it is precise enough to apply to nearby galaxies. For example, detailed Gaia observations of the Large Magellanic Cloud should allow astronomers to get a handle on dark matter speeds there.

This approach gives astronomers one more tool for the study of dark matter. As future observations allow us to pin down the properties of dark matter, we may be able to determine what dark matter really is.

Reference: Kipper, Rain, et al. “Back to the present: A general treatment for the tidal field from the wake of dynamical friction.” Astronomy & Astrophysics 680 (2023): A91.

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Construction of the Extremely Large Telescope (ELT) reached a milestone, with the structure of the dome completed just enough where engineers were able to rotate the dome’s skeleton for the first time.

ESO released a timelapse video this week of the dome’s movement, sped up from the actual snail’s pace of 1 centimeter per second. When the telescope is completed – currently set for sometime in 2028 — the rotation of the dome will allow the telescope to track objects in the night sky over the Chilean Atacama desert. The final operating speed will be at pace of 5 kilometers per hour.

Take note of the size of the humans moving about on the video. They appear like tiny ants compared to the immense size of the aptly named ELT.

ESO used the phrase “and yet it moves” in the video. That phrase comes from an apocryphal tale about Galileo Galilei, when he was forced to recant his stance that the Earth revolved around the Sun – as opposed to the stance of the Catholic Church, which held that Earth was an unmovable firmament. Legend has it that after his forced recantation, he muttered, “E pur si muove” (“And yet it moves”), meaning Earth. This tale has been refuted, but it is still a good story, and perhaps a portrayal of Galileo’s stubborn attitude about the importance of intellectual freedom.

ESO said the test was performed by engineers of Cimolai, the company contracted to design and build the ELT dome and telescope structure. The skeleton of the dome currently weighs about 2,500 tons, and will eventually weigh around 6100 tons when finished.

“This first test was carried out “manually” with special hydraulic devices, but eventually the enclosure will rotate via motorized bogies. While the motion of the dome is designed to be smooth, and was found to be during this test, the dome stands separate from the rest of the structure in order to limit vibrations to the telescope itself.”

The ELT will be the world’s largest optical/near-infrared telescope, located on top of a mountain named Cerro Armazones in the Atacama Desert of northern Chile.

This artist’s impression shows the European Extremely Large Telescope (E-ELT) in its enclosure. The E-ELT will be a 39-metre aperture optical and infrared telescope. ESO/L. Calçada

It will consist of a reflecting telescope with a 39.3-meter-diameter (130-foot) segmented primary mirror, with 798 hexagonal elements that all work together. It also has a 4.2 m (14 ft) diameter secondary mirror. The observatory aims to gather 100 million times more light than the human eye, 13 times more light than the largest optical telescopes, and be able to correct for atmospheric distortion with adaptive optics and eight laser guide star units, and will have multiple science instruments.

The ELT will search for extrasolar planets, with the goal of detecting water and organic molecules in protoplanetary discs around stars in the making to help answer fundamental questions about planet formation and evolution. Scientists also hope to study the formation of the first objects in the Universe such as primordial stars, primordial galaxies, and black holes. Another goal of the ELT is the possibility of making a direct measurement of the acceleration of the Universe’s expansion.

See ESO’s website for more information about the ELT.

The post The Extremely Large Telescope’s Dome is on the Move appeared first on Universe Today.

Universe Today has explored the potential for sending humans to Europa, Venus, Titan, and Pluto, all of which possess environmental conditions that are far too harsh for humans to survive. The insight gained from planetary scientists resulted in some informative discussions, and traveling to some of these far-off worlds might be possible, someday. In the final installment of this series, we will explore the potential for sending humans to a destination that has been the focus of scientific exploration and science folklore for more than 100 years: Mars aka the Red Planet.

Dr. Jordan Bretzfelder, who is a Postdoctoral Fellow in the Department of Earth, Planetary, and Space Sciences at the University of California, Los Angeles (UCLA), shares her insights on the viability of sending humans to Mars and how we should do it. So, should we send humans to Mars?

“Yes, I think there is immense value in sending humans to engage in scientific exploration on Mars,” Dr. Bretzfelder tells Universe Today. “Humans can make quick decisions about sampling and data acquisition and can move around certain obstacles and terrain with more ease and freedom than many types of robotic vehicles. This would also provide opportunities to study and develop technology to facilitate future planetary exploration.”

Countless robotic pioneers have explored the surface and atmosphere of Mars in incredible detail and continue to teach us whether Mars once had—or currently has—life. However, humans could provide an extra level of exploration since they won’t be hindered by waiting for instructions from Earth ground controllers, which can take anywhere from 5 to 20 minutes one way. If something goes wrong, human explorers can make on-the-spot decisions to find solutions, whereas robot explorers are faced with waiting for engineers back on Earth to find solutions, followed by sending instructions, and more waiting. Regarding technological advancements, a human mission will undoubtedly teach us how to live and work on Mars, and this includes testing shelters, food, bathroom facilities, and even combating the mental fatigue from being so far from Earth for a prolonged period. All things considered, what are the pros and cons of sending humans to Mars?

Dr. Bretzfelder tells Universe Today, “Pros are as above, and many examples of the benefits of humans in the field can be found in the history of the Apollo missions; instances where certain scientifically valuable rocks were collected due to the quick thinking and judgement of the astronauts. Cons include the difficulties involved in keeping astronauts alive and safe on a distant and environmentally complicated planetary surface. Additionally, the possibility of accidentally introducing terrestrial microbes to Mars is a potential risk.”

Whether it’s a robotic or human mission, NASA’s Office of Planetary Protection is responsible for ensuring that microbes don’t hitch a ride and contaminate extraterrestrial environments that we wish to explore, but especially to protect us from any microbes that could potentially be brought back to Earth.

Regarding the ongoing robotic exploration of Mars, there are presently seven active Mars orbiters from several nations teaching us more and more about the Red Planet and unlocking its secrets. On the surface, there are currently three active missions: NASA’s Curiosity and Perseverance rovers, and China’s Zhurong rover. Past successful surface missions include NASA’s Viking 1 and Viking 2 landers, Mars Pathfinder, Spirit and Opportunity rovers, Phoenix lander, and InSight lander. From marsquakes to finding evidence for past surface liquid water, each of these missions spent years unlocking the secrets of Mars, both above and below the surface. But what additional science could be conducted by a human mission compared to a robotic mission?

“As above, humans (within limits based on their suits and other equipment) have the ability to navigate terrain that may not be suitable for a rover or helicopter,” Dr. Bretzfelder tells Universe Today. “They also can make real time decisions in the field about sampling etc., meaning there is less delay in waiting for signals from mission control to guide the rovers. Humans are also very adaptable to changing conditions and can respond quickly to address any issues or unexpected situations during a mission.”

In terms of an actual human habitat on Mars, countless images, videos, movies, and television shows have depicted a human habitat on the Martian surface, with very little depiction of a human habitat below the surface. While this depiction might be for aesthetics, a habitat on the surface would provide ideal surveying and sampling conditions, along with far better communications with Earth. However, a habitat on the surface would also expose the crew to dangerous amounts of solar radiation since Mars does not possess either an ozone layer or magnetic field like the Earth, both of which protect us from solar storms and other cosmic rays.

Artist’s concept for a crewed mission on Mars. (Credit: NASA/Clouds AO/SEArch)

In contrast, another type of human habitat could be below the surface, with past studies identifying the use of lava tubes for human settlements to shield them from the harmful solar radiation. However, any surface ventures could become tedious, along with communications with Earth becoming more complicated, even if a communications array was above-ground. Therefore, if humans were to travel to Mars, should it be above the surface or below?

Dr. Bretzfelder tells Universe Today, “An above surface mission, similar to the Apollo and upcoming Artemis missions would be the most feasible given the technology available and would limit impact to the Martian surface by simply operating above ground rather than excavating below ground. Samples or cores taken from depth may be scientifically valuable though.”

This discussion comes as NASA prepares to send humans back to the Moon as part of its Moon to Mars Architecture while SpaceX develops its Starship with the goal of sending humans to Mars, someday. China announced plans in 2021 to send their own astronauts to the Red Planet in 2033, with follow-up launches occurring every two years afterwards. Additionally, NASA has the goal of sending humans to Mars sometime in the 2030s.

“It is an exciting time to be able to seriously consider this type of exploration, and as we return to the Moon, we will likely learn valuable lessons to enable human exploration of Mars,” Dr. Bretzfelder tells Universe Today.

Will we ever send humans to Mars? Will such a mission achieve greater scientific objectives than the myriad of robotic missions sent to the Red Planet, and what could a human mission to Mars teach us about living and working so far from Earth? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

The post Should We Send Humans to Mars? appeared first on Universe Today.

A recent study accepted to The Planetary Science Journal investigates how the organic hazes that existed on Earth between the planet’s initial formation and 500 million years afterwards, also known as Hadean geologic eon, could have contained the necessary building blocks for life, including nucleobases and amino acids. This study holds the potential to not only help scientists better understand the conditions on an early Earth, but also if these same conditions on Saturn’s largest moon, Titan, could produce the building blocks of life, as well.

Here, Universe Today discusses this recent study with Dr. Ben K. D. Pearce, who is a Postdoctoral Fellow in the Morton K. Blaustein Department of Earth & Planetary Sciences at Johns Hopkins University and lead author of the study, regarding the study’s findings, potential follow-up research, NASA’s upcoming Dragonfly mission to Titan, and whether he thinks there’s life on Titan.

Dr. Pearce tells Universe Today about how past lab studies involving Carl Sagan discovered that the highest dilution (or addition of a solvent like water) to make the chemical reactions work was 100 micromolar, or approximately 10 parts per million (ppm). If the dilution is too strong, the molecules in the chemical mixture wouldn’t find each other, he says.

“After all, early Earth was a hazy place, much akin to Saturn’s Moon Titan,” Dr. Pearce tells Universe Today. “This is because over 4 billion years ago, Earth had an atmosphere rich in hydrogen, methane, and nitrogen, similar to Titan! What’s interesting about these haze particles, is that they are essentially biomolecule snowflakes, i.e., big aggregates of life’s building blocks bonded together. When these particles settled onto Earth’s surface, over 4 billion years ago, and fell into ponds, the bonds would break, and you could get a pond rich in life’s building blocks. We wanted to know if this source could exceed the 100 micromolar threshold in ponds, which could be concentrated enough for them to react and begin the process of forming the first information molecules like ribonucleic acid (RNA).”

Artist’s impression of a hazy and ancient Earth. (Credit: NASA’s Goddard Space Flight Center/Francis Reddy)

For the study, the researchers created organic hazes in a laboratory setting under atmospheric conditions containing between 0.5 percent and 5 percent methane and analyzed the hazes for traces of amino acids and nucleobases using a gas chromatograph/mass spectrometer (GC/MS). Additionally, they heated samples up to 200 degrees Celsius (392 degrees Fahrenheit) to simulate the samples resting on an uninhabitable surface, as well. The team then compared their results to computer models to investigate the number of nucleobases that would be present in these same environments.

Artist’s illustration of a very violent early Earth. (Credit: NASA)

“When we modeled the pond concentrations of nucleobases from organic hazes (making use of our experimental data), we discovered that this source may be the richest, most long-lasting source that we’ve modeled to date,” Dr. Pearce tells Universe Today. “As a reminder, all sources we’ve studied to date (meteorites, interplanetary dust, and atmospheric HCN) have led to below 100 micromolar concentrations; however, now we have finally found a source that breaches up towards this threshold.”

In the end, the team discovered that nucleobases could exist in “warm little ponds” on Earth during the Hadean geologic eon. With the heating experiment, the team ascertained that such samples could not survive on a hot surface. Finally, they concluded that organic hazes could produce the building blocks of life only in a methane-rich atmosphere on ancient Earth, “but not so rich as to create an uninhabitable surface,” Dr. Pearce notes to Universe Today. Given these incredible findings, what follow-up research is being conducted or planned?

“I am presently building a new experimental setup to be used in my laboratory in the Department of Earth, Atmospheric, and Planetary Sciences at Purdue University, which opens this fall 2024,” Dr. Pearce tells Universe Today. “This lab is called the Origins and Astrobiology Research Laboratory. This experiment will allow my new research group to simultaneously model the atmospheric chemistry (e.g., HCN and organic haze production) and pond chemistry of early Earth. Our initial goal will be to use this to demonstrate the production of the first information molecules of life, such as RNA, in a simulated early Earth environment.”

This study comes as NASA is planning to send its Dragonfly mission to Titan, which currently has a planned launch date of July 2028 and landing on Titan’s surface sometime in 2034 in the “Shangri-La” dune fields. Dragonfly is a quadcopter whose goal will be to “hop” around Titan searching for evidence of Titan’s potential habitability, and currently has a planned mission timeline of 10 years with the science phase comprising 3.3 years. Its scientific payload will consist of a mass spectrometer, gamma-ray and neutron spectrometer, geophysics and meteorology package, and a suite of microscopic and panoramic cameras.

Dragonfly is slated to operate during the Titan day and remain on the ground at night, with each lasting approximately 8 Earth days or 192 hours. It is currently hypothesized that Dragonfly will be capable of flying up to 16 kilometers (10 miles) on a single battery charge, with its batteries consisting of a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) that will charge during the night. MMRTGs have a successful history on space missions, as they are currently used to power NASA’s Curiosity and Perseverance rovers on Mars. But how will Dragonfly contribute to or refute this study’s findings?

Artist’s impression of NASA’s Dragonfly quadcopter exploring the surface of Titan. (Credit: NASA)

Dr. Pearce tells Universe Today, “Given that there are tons of organic haze on Titan, we could expect that the surface contains preserved organic haze particles rich in life’s building blocks. Dragonfly will contain a mass spectrometer and will be able to characterize the building blocks of life in these particles to potentially validate our laboratory studies.”

Titan has a rich history of exploration, as numerous spacecraft over several decades have allowed us to gain greater insights into this mysterious world, which is not only the second-largest moon in the entire solar system but the only moon with a thick atmosphere. While the cameras onboard NASA’s Pioneer 11, Voyager 1, and Voyager 2 spacecraft were unable to image Titan’s surface due to the moon’s thick and hazy atmosphere, NASA’s Cassini spacecraft successfully used its infrared cameras to image Titan’s surface for the first time. It was these images that confirmed previous hypotheses that Titan possessed lakes of liquid methane and ethane that can only exist in extremely cold temperatures, with Titan’s surface temperature being minus 179 degrees Celsius (minus 290 degrees Fahrenheit).

Images of Titan obtained by NASA’s Cassini spacecraft on April 16, 2005: natural color composite (left), monochrome (center), and false-color composite (right). (Credit: NASA/JPL/Space Science Institute)

Cassini carried with it the European Space Agency’s Huygens probe, which detached from the orbiting spacecraft and landed on Titan’s surface, sending back surface features of rounded rocks that could have only formed under liquid conditions. But, given that Titan could resemble an early Earth with its methane atmosphere and liquid lakes, will we find life on Titan?

“The only habitable environment on Titan is deep in the subsurface, which is not easy to get to without a drill or a geyser spewing stuff onto the surface,” Dr. Pearce tells Universe Today. “Thus, I’m not sure we will even be looking in the best places for decades beyond Dragonfly. It is also hard for me to imagine an origin of life on Titan, given that our current best hypotheses involve wet-dry cycles of ponds that would not be available on -180 C Titan. However, if I have learned anything from science in the past decade, it’s that we are often proven wrong by new findings, and I absolutely welcome it! It’s always better to look, just in case!”

How will this recent study contribute to finding life on Titan, and what will Dragonfly teach us about Titan’s habitability 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 How Did Life Get Started on Earth? Atmospheric Haze Might Have Been the Key appeared first on Universe Today.

The field of exoplanet study continues to grow by leaps and bounds. As of the penning of this article, 5,572 extrasolar planets have been confirmed in 4,150 systems (with another 10,065 candidates awaiting confirmation. Well, buckle up because six more exoplanets have been confirmed around TOI-1136, a Sun-like star located roughly 276 light-years from Earth. This star is less than 700 million years old, making it relatively young compared to our own (4.6 billion years). This system will allow astronomers to observe how systems like our own have evolved with time.

The six-planet system was confirmed by the TESS Keck Survey, an international team of astronomers that searches for exoplanets by combing data obtained by the Transiting Exoplanet Survey Satellite (TESS) and the W.M. Keck Observatory (of which UC Riverside planetary astrophysics professor Stephen Kane is the principal investigator). The details of the six-planet system were presented in a series of papers that appeared in The Astronomical Journal. In the seventeenth and latest paper in the series, the survey team presented precise mass measurements of the six exoplanets, details about their orbits, and the characteristics of their atmospheres.

To date, most of the exoplanets observed by astronomers have been either individual discoveries or one of just a few planets. But in some cases, such as Kepler-90 and TRAPPIST-1, astronomers have observed many planets in a single system (8 and 7, respectively). Depending on the age of their parent star, these systems present astronomers with the opportunity to observe how multi-planet systems formed and evolved. In the case of TOI-1136, its age sets it apart from many known systems, being merely 700 million years old.

Artist’s impression of the planetary system around Kepler-90, a Sun-like star 2,545 light years from Earth. Credits: NASA

Tara Fetherolf, a visiting assistant professor of astrophysics at Cal State San Marcos and co-author of a new paper, explained in a UC Riverside News release:

“Because few star systems have as many planets as this one does, it’s getting close in size to our own Solar System. It’s both similar enough and different enough that we can learn a lot. This gives us a look at planets right after they’ve formed, and solar system formation is a hot topic. Any time we find a multi-planet system it gives us more information to inform our theories about how systems come to be and how our system.”

Initial observations of the system were made in 2019 using TESS, which was followed up with observations using the High-Resolution Echelle Spectrometer (HIRES) at the W.M. Keck Observatory and the Automated Planet Finder (APF) at the Lick Observatory. The latter observations allowed the team to precisely constrain the mass of the planets using the Radial Velocity measurements (where slight variations in the star’s motion indicate the gravitational forces acting on it). This yielded estimates of about 3.5 (TOI-1135 b) to 9.7 (TOI-1135 f) Earth masses, placing them between Super Earths to Mini-Neptunes.

The team also used Transit Timing variations, where dips in a star’s luminosity are used to determine the presence of planets (and their size). They then created computer models where the velocity measurements were layered over the transit data, yielding more information about the system. Typically, young stars are difficult to study because they are so active, possessing powerful magnetic fields, sunspots, and powerful solar flares that influence their planets by affecting their atmospheres. Since all the planets observed around TOI-1136 are of a similar age, they likely formed under similar conditions.

An amusing rendition of the TOI-1136 system if each body in the system were a duck or duckling. Credit: Rae Holcomb/UCI

And since the planets of this system are relatively close to each other, the team was able to measure something hard to gauge in other systems. As Kane summarized:

“Young stars misbehave all the time. They’re very active, just like toddlers. That can make high-precision measurements difficult. This will help us not only do a one-to-one comparison of how planets change with time but also how their atmospheres evolved at different distances from the star, which is perhaps the most key thing.”

The results of this study could have far-reaching implications for exoplanet research and the search for life in the cosmos (astrobiology). According to the most recent fossilized evidence, life emerged on Earth during the Archaean Eon (ca. 3.9 billion years ago), almost immediately after it formed. While many of TOI-1136’s planets orbit too closely and are subject to too much radiation to make life likely, the team hopes that observations of this system will ultimately answer questions of how our planet and life as we know it came to be.

“Are we rare?” said Kane. “I’m increasingly convinced our system is highly unusual in the Universe. Finding systems so unlike our own makes it increasingly clear how our Solar System fits into the broader context of formation around other stars.”

Further Reading: UC Riverside, The Astronomical Journal

The post Six Planets Found Orbiting an Extremely Young Star appeared first on Universe Today.

When a prominent star in the night sky suddenly dims, it generates a lot of interest. That’s what happened with the red supergiant star Betelgeuse between November 2019 and May 2020. Betelgeuse will eventually explode as a supernova. Was the dimming a signal that the explosion was imminent?

No, and new research helps explain why.

Headline writers couldn’t resist the supernova angle, even though that explanation was never very likely. Eventually, it became clear that ejected dust from the star caused the dimming. New research based on observations before, during, and after the Great Dimming Event (GDE) supports the idea that dust from the star itself caused Betelgeuse’s drop in brightness.

A research letter titled “Images of Betelgeuse with VLTI/MATISSE across the Great Dimming” presents the infrared observations of Betelgeuse. The observations capture the star before, during, and after the GDE. The lead author is Julien Drevon, from the Université Côte d’Azur, France, and the European Southern University.

“To better understand the dimming event, we used mid-infrared long-baseline spectro-interferometric measurements of Betelgeuse taken with the VLTI/MATISSE instrument before (Dec. 2018), during (Feb. 2020) and after (Dec. 2020) the GDE,” the research letter states. In particular, their observations focus on silicon monoxide (SiO.)

The authors of the new research outline three steps in the process that created the GDE.

Step One

The GDE started with shocks deep inside Betelgeuse. They generated a convective outflow of plasma that brought material to the star’s surface. Researchers detected a strong shock in February 2018 and a weaker one in January 2019. The second, weaker shock boosted the effect of the stronger shock that preceded it, generating a progressive plasma flow at the surface of Betelgeuse’s photosphere.

Step Two

The plasma flowing to the photosphere’s surface created a hot spot. Hubble UV observations of Betelgeuse revealed the presence of a luminous, hot, dense structure in the star’s southern hemisphere, between the photosphere and the chromosphere.

Step Three

Stellar material detaches from the photosphere and forms a gas cloud above Betelgeuse’s surface. A colder region forms under this cloud as a dark spot. Since it’s cooler, dust is allowed to condense above this region and in the part of the cloud above it. That dust is what blocked some of Betelgeuse’s luminosity, causing the GDE.

Previous research revealed this three-step process behind the GDE. The authors of the new research article set out to observe Betelgeuse’s close circumstellar environment to probe and monitor its geometry. In the wavelength range they worked in, SiO spectral features are prominent, and they’re used to understand what happened with the red supergiant. In astronomy, SiO is used as a tracer for shocked gas in stellar outflows since it persists at high temperatures.

This figure from the research letter shows some of the data the researchers worked with. The top panel shows the absolute spectra during each observed epoch. The bottom panel shows the relative flux for the SiO bands. The bands are deeper during the GDE than either before or after. Image Credit: J. Drevon et al. 2024.

In their article, the authors focus on the SiO (2-0) band and what it signifies. They note how the band’s intensity contrast increases by 14% during the GDE. “Therefore, it seems that during the GDE, we observe brighter structures in the line of sight,” they explain.

Next, they note a 50% decrease in intensity contrast in December 2020. What does it mean?

“The SiO (2–0) opacity depth map shows, therefore, strong temporal variations within 2 years, indicative of vigorous changes in the star’s environment in this time span,” they write.

Their observations also suggest “the presence of an infrared excess in the pseudo continuum during the GDE, which has been interpreted as new hot dust formed,” Drevon and his colleagues write.

This figure from the research article explains some of what the researchers found. The middle column is particularly interesting because it’s a reconstruction of the SiO (2-0) absorption band onto Betelgeuse’s surface for each of the three observed epochs. The third column is similar but shows the SiO (2-0) optical depth. Overall, they constrain the geometry of the dust feature that caused the GDE. Image Credit: J. Drevon et al. 2024.

It seems like the Great Dimming is no longer the mystery it once was. It also shows that Occam’s Razor is alive and well: “The explanation that requires the fewest assumptions is usually correct.”

The supernova proposal was fun for a while, and one day, Betelgeuse will explode as a supernova. But before it ever does, there are likely going to be several more episodes of dimming. For now, the authors say that the star is returning to normal.

“The Dec. 2020 observations suggest that Betelgeuse seems to be returning to a gas and surface environment similar to the one observed in Dec. 2018,” they write, “but with smoother structures, maybe
due to the unusual amount of dust recently formed during the GDE in the line of sight.”

Case closed?

The post Betelgeuse. Before, During and After the Great Dimming appeared first on Universe Today.

Within almost every galaxy there is a supermassive black hole. This by itself implies some kind of formative connection between the two. We have also observed how gas and dust within a galaxy can drive the growth of galactic black holes, and how the dynamics of black holes can both drive star formation or hinder it depending on how active a black hole is. But one area where astronomers still have little information is how galaxies and their black holes interacted in the early Universe. Did black holes drive the formation of galaxies, or did early galaxies fuel the growth of black holes? A recent study suggests the two evolved hand in hand.

It’s difficult to observe the complex dynamics of black holes and galaxies in the early cosmos, but one way to study them is to compare the mass of a galactic black hole with the mass of all the stars in its galaxy. This can be expressed as a ratio MBH / M* to see how it varies over time. This means measuring this ratio at ever-increasing redshifts, since the greater the redshift, the younger the galaxy.

For this study, the team looked at 61 galaxies with active galactic nuclei (AGNs) as identified by X-ray observations. The luminosity of the AGNs gives us an idea of the black hole’s mass. They then added JWST observations of these galaxies from the COSMOS-Web and PRIMER surveys. From these, they could get the infrared luminosity of the galaxies, which let them determine their total stellar mass.

The mass ratios of this study (red dots) compared to earlier studies. Credit: Tanaka, et al

The galaxies they observed have redshifts between z = 0.7 and z = 2.5, meaning that the galaxies are seen as they were 6 billion to 11 billion years ago. What they found is that galaxies and their black holes grow hand in hand. As the galaxy increases in mass, so does the black hole. The relationship is very roughly linear, though the ratio favors the black hole slightly at higher redshifts. For you math geeks, the team found the ratio varies as MBH / M* = (1 + z)0.37. This means the black holes grow at a slightly slower rate than the galaxies.

Unfortunately, the uncertainty of this result is rather large. It will take more observations, particularly at the higher redshift end, to pin down the relation more precisely. But in the coming years, astronomers should be able to gather this data. This study shows that galaxies and their black holes grow at similar rates across billions of years. Future studies will help us understand the more subtle connections between them.

Reference: Tanaka, Takumi S., et al. “The MBH-M* relation up to z = 2 through decomposition of COSMOS-Web NIRCam images.” arXiv preprint arXiv:2401.13742 (2024).

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