ST/ Astronomers measure heaviest black hole pair ever found

Paradigm

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Paradigm

30 min readMar 8, 2024

Space biweekly vol.93, 23rd February — 8th March

TL;DR

Gemini North telescope data reveals the heaviest supermassive black hole pair ever recorded by astronomers.
The merger of two supermassive black holes, long theorized, is observed for the first time, shedding light on its rarity in the Universe.
Luminous stars influence planet formation until a tipping point, where radiation disperses material in protoplanetary discs.
Researchers identify a unique scar on a white dwarf star, marking the ingestion of surrounding planets and asteroids.
Water vapor discovered in the disc around a young star provides insights into planet formation and the distribution of water in stable discs.
Astrobiologists devise a method to determine ocean temperatures on distant worlds by analyzing the thickness of their ice shells.
Astronomers characterize a record-breaking quasar, the brightest and most luminous ever observed, with a supermassive black hole growing at an unprecedented rate.
Observational evidence supports the creation of rare heavy elements in the aftermath of a neutron star merger-triggered cataclysmic explosion.
A new computer model accurately simulates Moon dust, enhancing the potential for smoother and safer Lunar robot teleoperations.
NASA’s James Webb Space Telescope aids astronomers in uncovering early universe conditions, providing a detailed picture of the Wolf — Lundmark — Melotte galaxy and its ancient star formation.
And more!

Space industry in numbers

The global smart space market size is projected to grow from USD 9.4 billion in 2020 to USD 15.3 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 10.2% during the forecast period. The increasing venture capital funding and growing investments in smart space technology to drive market growth.

Analysts at Morgan Stanley and Goldman Sachs have predicted that economic activity in space will become a multi-trillion-dollar market in the coming decades. Morgan Stanley’s Space Team estimates that the roughly USD 350 billion global space industry could surge to over USD 1 trillion by 2040.

Source: Satellite Industry Association, Morgan Stanley Research, Thomson Reuters. *2040 estimates

Space industry news

Latest research

The Central Kinematics and Black Hole Mass of 4C+37.11

by Tirth Surti, Roger W. Romani, Julia Scharwächter, Alison Peck, Greg B. Taylor in The Astrophysical Journal

Nearly every massive galaxy hosts a supermassive black hole at its center. When two galaxies merge, their black holes can form a binary pair, meaning they are in a bound orbit with one another. It’s hypothesized that these binaries are fated to eventually merge, but this has never been observed. The question of whether such an event is possible has been a topic of discussion amongst astronomers for decades. In a recently published paper, a team of astronomers have presented new insight into this question.

The team used data from the Gemini North telescope in Hawai’i, one half of the International Gemini Observatory operated by NSF’s NOIRLab, which is funded by the U.S. National Science Foundation, to analyze a supermassive black hole binary located within the elliptical galaxy B2 0402+379. This is the only supermassive black hole binary ever resolved in enough detail to see both objects separately, and it holds the record for having the smallest separation ever directly measured — a mere 24 light-years. While this close separation foretells a powerful merger, further study revealed that the pair has been stalled at this distance for over three billion years, begging the question; what’s the hold-up?

To better understand the dynamics of this system and its halted merger the team looked to archival data from Gemini North’s Gemini Multi-Object Spectrograph (GMOS), which allowed them to determine the speed of the stars within the vicinity of the black holes.

“The excellent sensitivity of GMOS allowed us to map the stars’ increasing velocities as one looks closer to the galaxy’s center,” said Roger Romani, Stanford University physics professor and co-author of the paper. “With that, we were able to infer the total mass of the black holes residing there.”

Radial velocity (V) and velocity dispersion (σ) maps of pPXF measurements in the Voronoi bins. The origin is the AGN location, determined from the wings of the [N ii] emission lines. Solid contours mark 0.9×,0.8×,…0.2× the peak surface brightness and dashed lines separate quadrants along the major and minor axes.

The team estimates the binary’s mass to be a whopping 28 billion times that of the Sun, qualifying the pair as the heaviest binary black hole ever measured. Not only does this measurement give valuable context to the formation of the binary system and the history of its host galaxy, but it supports the long-standing theory that the mass of a supermassive binary black hole plays a key role in stalling a potential merger.

“The data archive serving the International Gemini Observatory holds a gold mine of untapped scientific discovery,” says Martin Still, NSF program director for the International Gemini Observatory. “Mass measurements for this extreme supermassive binary black hole are an awe-inspiring example of the potential impact from new research that explores that rich archive.”

Understanding how this binary formed can help predict if and when it will merge — and a handful of clues point to the pair forming via multiple galaxy mergers. The first is that B2 0402+379 is a ‘fossil cluster,’ meaning it is the result of an entire galaxy cluster’s worth of stars and gas merging into one single massive galaxy. Additionally, the presence of two supermassive black holes, coupled with their large combined mass, suggests they resulted from the amalgamation of multiple smaller black holes from multiple galaxies.

Following a galactic merger, supermassive black holes don’t collide head-on. Instead they begin slingshotting past each other as they settle into a bound orbit. With each pass they make, energy is transferred from the black holes to the surrounding stars. As they lose energy, the pair is dragged down closer and closer until they are just light-years apart, where gravitational radiation takes over and they merge. This process has been directly observed in pairs of stellar-mass black holes — the first ever recorded instance being in 2015 via the detection of gravitational waves — but never in a binary of the supermassive variety.

I image isophote contours (black) and MGE fit ellipses (red). Top: the full region. Bottom: the IFU region with kinematic measurements. The yellow regions correspond to masked pixels in the MGE fits.

With new knowledge of the system’s extremely large mass, the team concluded that an exceptionally large number of stars would have been needed to slow the binary’s orbit enough to bring them this close. In the process, the black holes seem to have flung out nearly all the matter in their vicinity, leaving the core of the galaxy starved of stars and gas. With no more material available to further slow the pair’s orbit, their merger has stalled in its final stages.

“Normally it seems that galaxies with lighter black hole pairs have enough stars and mass to drive the two together quickly,” said Romani. “Since this pair is so heavy it required lots of stars and gas to get the job done. But the binary has scoured the central galaxy of such matter, leaving it stalled and accessible for our study.”

Whether the pair will overcome their stagnation and eventually merge on timescales of millions of years, or continue in orbital limbo forever, is yet to be determined. If they do merge, the resulting gravitational waves would be a hundred million times more powerful than those produced by stellar-mass black hole mergers. It’s possible the pair could conquer that final distance via another galaxy merger, which would inject the system with additional material, or potentially a third black hole, to slow the pair’s orbit enough to merge. However, given B2 0402+379’s status as a fossil cluster, another galactic merger is unlikely.

“We’re looking forward to follow-up investigations of B2 0402+379’s core where we’ll look at how much gas is present,” says Tirth Surti, Stanford undergraduate and the lead author on the paper. “This should give us more insight into whether the supermassive black holes can eventually merge or if they will stay stranded as a binary.”

A far-ultraviolet–driven photoevaporation flow observed in a protoplanetary disk

by Olivier Berné, Emilie Habart, Els Peeters, Ilane Schroetter, et al in Science

To find out how planetary systems such as our Solar System form, an international research team including scientists from the University of Cologne studied a stellar nursery, the Orion Nebula, using the James Webb Space Telescope (JWST). By observing a protoplanetary disc named d203–506, they discovered the key role massive stars play in the formation of planetary systems that are less than a million years old. The study, led by Dr Olivier Berné from the National Centre for Scientific Research (CNRS) in Toulouse.

These stars, which are around ten times more massive, and, more importantly, 100,000 times more luminous than the Sun, expose any planets forming in such systems nearby to very intense ultraviolet radiation. Depending on the mass of the star at the centre of the planetary system, this radiation can either help planets to form, or alternatively prevent them from doing so by dispersing their matter. In the Orion Nebula, the scientists found that, due to the intense irradiation from massive stars, a Jupiter-like planet would not be able to form in the planetary system d203–506.

The team encompasses a wide range of experts from areas such as instrumentation, data reduction and modelling. The data from the JWST were combined with data collected with the Atacama Large Millimeter Array (ALMA) in order to constrain the physical conditions in the gas. The calculated rate at which the disk lost mass implies that the whole disk will evaporate faster than it would take for a giant planet to form.

“It is great that so many contributions from the team over the years, including the planning of the observations and the evaluation the data, are bearing fruit in the form of these results that represent a significant step forward in understanding the formation of planetary systems,” said Dr Yoko Okada from the University of Cologne’s Institute of Astrophysics.

The JWST data in the Orion Nebula is very rich, keeping scientists busy to conduct various detailed analyses in the fields of star- and planet-formation as well as the evolution of the interstellar medium.

Discovery of Magnetically Guided Metal Accretion onto a Polluted White Dwarf

by Stefano Bagnulo, Jay Farihi, John D. Landstreet, Colin P. Folsom in The Astrophysical Journal Letters

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

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

The scar the team observed is a concentration of metals imprinted on the surface of the white dwarf WD 0816–310, the Earth-sized remnant of a star similar to, but somewhat larger than, our Sun. “We have demonstrated that these metals originate from a planetary fragment as large as or possibly larger than Vesta, which is about 500 kilometres across and the second-largest asteroid in the Solar System,” says Jay Farihi, a professor at University College London, UK, and co-author on the study.

Stokes spectra of WD 0816–310, with flux normalized to the continuum shown in panel (a) and V/I plotted in panel (b).

The observations also provided clues to how the star got its metal scar. The team noticed that the strength of the metal detection changed as the star rotated, suggesting that the metals are concentrated on a specific area on the white dwarf’s surface, rather than smoothly spread across it. They also found that these changes were synchronised with changes in the white dwarf’s magnetic field, indicating that this metal scar is located on one of its magnetic poles. Put together, these clues indicate that the magnetic field funneled metals onto the star, creating the scar.

“Surprisingly, the material was not evenly mixed over the surface of the star, as predicted by theory. Instead, this scar is a concentrated patch of planetary material, held in place by the same magnetic field that has guided the infalling fragments,” says co-author John Landstreet, a professor at Western University, Canada, who is also affiliated with the Armagh Observatory and Planetarium. “Nothing like this has been seen before.”

To reach these conclusions, the team used a ‘Swiss-army knife’ instrument on the VLT called FORS2, which allowed them to detect the metal scar and connect it to the star’s magnetic field. “ESO has the unique combination of capabilities needed to observe faint objects such as white dwarfs, and sensitively measure stellar magnetic fields,” says Bagnulo. In their study, the team also relied on archival data from the VLT’s X-shooter instrument to confirm their findings.

Harnessing the power of observations like these, astronomers can reveal the bulk composition of exoplanets, planets orbiting other stars outside the Solar System. This unique study also shows how planetary systems can remain dynamically active, even after ‘death’.

Resolved ALMA observations of water in the inner astronomical units of the HL Tau disk

by Stefano Facchini, Leonardo Testi, Elizabeth Humphreys, Mathieu Vander Donckt, Andrea Isella, Ramon Wrzosek, Alain Baudry, Malcom D. Gray, Anita M. S. Richards, Wouter Vlemmmings in Nature Astronomy

Researchers have found water vapour in the disc around a young star exactly where planets may be forming. Water is a key ingredient for life on Earth, and is also thought to play a significant role in planet formation. Yet, until now, we had never been able to map how water is distributed in a stable, cool disc — the type of disc that offers the most favourable conditions for planets to form around stars. The new findings were made possible thanks to the Atacama Large Millimeter/submillimeter Array (ALMA), in which the European Southern Observatory (ESO) is a partner.

“I had never imagined that we could capture an image of oceans of water vapour in the same region where a planet is likely forming,” says Stefano Facchini, an astronomer at the University of Milan, Italy, who led the study. The observations reveal at least three times as much water as in all of Earth’s oceans in the inner disc of the young Sun-like star HL Tauri, located 450 light-years away from Earth in the constellation Taurus.

“It is truly remarkable that we can not only detect but also capture detailed images and spatially resolve water vapour at a distance of 450 light-years from us ,” adds co-author Leonardo Testi, an astronomer at the University of Bologna, Italy. The ‘spatially resolved’ observations with ALMA allow astronomers to determine the distribution of water in different regions of the disc.
“Taking part in such an important discovery in the iconic HL Tauri disc was beyond what I had ever expected for my first research experience in astronomy,” adds Mathieu Vander Donckt from the University of Liege, Belgium, who was a master’s student when he participated in the research.

A significant amount of water was found in the region where a known gap in the HL Tauri disc exists. Ring-shaped gaps are carved out in gas- and dust-rich discs by orbiting young planet-like bodies as they gather up material and grow. “Our recent images reveal a substantial quantity of water vapour at a range of distances from the star that include a gap where a planet could potentially be forming at the present time,” says Facchini. This suggests that this water vapour could affect the chemical composition of planets forming in those regions.

Continuum intensity and water vapour moment maps.

Observing water with a ground-based telescope is no mean feat as the abundant water vapour in Earth’s atmosphere degrades the astronomical signals. ALMA, operated by ESO together with its international partners, is an array of telescopes in the Chilean Atacama Desert at about 5000 metres elevation that was built in a high and dry environment specifically to minimise this degradation, providing exceptional observing conditions. “To date, ALMA is the only facility able to spatially resolve water in a cool planet-forming disc,” says co-author Wouter Vlemmings, a professor at the Chalmers University of Technology in Sweden.

“It is truly exciting to directly witness, in a picture, water molecules being released from icy dust particles,” says Elizabeth Humphreys, an astronomer at ESO who also participated in the study. The dust grains that make up a disc are the seeds of planet formation, colliding and clumping into ever larger bodies orbiting the star. Astronomers believe that where it is cold enough for water to freeze onto dust particles, things stick together more efficiently — an ideal spot for planet formation.

“Our results show how the presence of water may influence the development of a planetary system, just like it did some 4.5 billion years ago in our own Solar System,” Facchini adds.

With upgrades happening at ALMA and ESO’s Extremely Large Telescope (ELT) coming online within the decade, planet formation and the role water plays in it will become clearer than ever. In particular METIS, the Mid-infrared ELT Imager and Spectrograph, will give astronomers unrivalled views of the inner regions of planet-forming discs, where planets like Earth form.

Ice‐Ocean Interactions on Ocean Worlds Influence Ice Shell Topography

by J. D. Lawrence, B. E. Schmidt, J. J. Buffo, P. M. Washam, C. Chivers, S. Miller in Journal of Geophysical Research: Planets

Cornell University astrobiologists have devised a novel way to determine ocean temperatures of distant worlds based on the thickness of their ice shells, effectively conducting oceanography from space.

Available data showing ice thickness variation already allows a prediction for the upper ocean of Enceladus, a moon of Saturn, and a NASA mission’s planned orbital survey of Europa’s ice shell should do the same for the much larger Jovian moon, enhancing the mission’s findings about whether it could support life.

The researchers propose that a process called “ice pumping,” which they’ve observed below Antarctic ice shelves, likely shapes the undersides of Europa’s and Enceladus’ ice shells, but should also operate at Ganymede and Titan, large moons of Jupiter and Saturn, respectively. They show that temperature ranges where the ice and ocean interact — important regions where ingredients for life may be exchanged — can be calculated based on an ice shell’s slope and changes in water’s freezing point at different pressures and salinities.

“If we can measure the thickness variation across these ice shells, then we’re able to get temperature constraints on the oceans, which there’s really no other way yet to do without drilling into them,” said Britney Schmidt, associate professor of astronomy and of earth and atmospheric sciences. “This gives us another tool for trying to figure out how these oceans work. And the big question is, are things living there, or could they?”

In 2019, using the remotely operated Icefin robot, Schmidt’s team observed ice pumping inside a crevasse beneath Antarctica’s Ross Ice Shelf. The researchers mapped ranges of potential shell thickness, pressure and salinity for ocean worlds with varying gravity and concluded that ice pumping would occur in the most probable scenarios, though not in all. They found that ice-ocean interactions on Europa may be similar to those observed beneath the Ross Ice Shelf — evidence that such regions may be some of the most Earth-like on alien worlds, said Justin Lawrence, a visiting scholar at the Cornell Center for Astrophysics and Planetary Science and a program manager at Honeybee Robotics.

Thermohaline ice pump circulation below a generalized ice shelf.

NASA’s Cassini probe generated data sufficient to predict a temperature range for Enceladus’ ocean, based on the slope of its ice shell from poles to equator: minus 1.095 degrees to minus 1.272 degrees Celsius. Knowing temperatures informs understanding of how heat flows through oceans and how they circulate, affecting habitability.

The researchers expect ice pumping to be weak at Enceladus, a small moon (the width of Arizona) with dramatic topography, while at larger Europa — nearly the size of Earth’s moon — they predict it acts quickly to smooth and flatten the ice shell’s base. Schmidt said the work demonstrates how research investigating climate change on Earth can also benefit planetary science, a reason NASA has supported Icefin’s development.

“There’s a connection between the shape of the ice shell and the temperature in the ocean,” Schmidt said. “This is a new way to get more insight from ice shell measurements that we hope to be able to get for Europa and other worlds.”

The accretion of a solar mass per day by a 17-billion solar mass black hole

by Christian Wolf, Samuel Lai, Christopher A. Onken, Neelesh Amrutha, Fuyan Bian, Wei Jeat Hon, Patrick Tisserand, Rachel L. Webster in Nature Astronomy

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

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

“We have discovered the fastest-growing black hole known to date. It has a mass of 17 billion Suns, and eats just over a Sun per day. This makes it the most luminous object in the known Universe,” says Christian Wolf, an astronomer at the Australian National University (ANU) and lead author of the study. The quasar, called J0529–4351, is so far away from Earth that its light took over 12 billion years to reach us.

The matter being pulled in toward this black hole, in the form of a disc, emits so much energy that J0529–4351 is over 500 trillion times more luminous than the Sun. “All this light comes from a hot accretion disc that measures seven light-years in diameter — this must be the largest accretion disc in the Universe,” says ANU PhD student and co-author Samuel Lai. Seven light-years is about 15,000 times the distance from the Sun to the orbit of Neptune.

And, remarkably, this record-breaking quasar was hiding in plain sight. “It is a surprise that it has remained unknown until today, when we already know about a million less impressive quasars. It has literally been staring us in the face until now,” says co-author Christopher Onken, an astronomer at ANU. He added that this object showed up in images from the ESO Schmidt Southern Sky Survey dating back to 1980, but it was not recognised as a quasar until decades later.

Artist’s impression of the record-breaking quasar J0529–4351.

Finding quasars requires precise observational data from large areas of the sky. The resulting datasets are so large, researchers often use machine-learning models to analyse them and tell quasars apart from other celestial objects. However, these models are trained on existing data, which limits the potential candidates to objects similar to those already known. If a new quasar is more luminous than any other previously observed, the programme might reject it and classify it instead as a star not too distant from Earth.

An automated analysis of data from the European Space Agency’s Gaia satellite passed over J0529–4351 for being too bright to be a quasar, suggesting it to be a star instead. The researchers identified it as a distant quasar last year using observations from the ANU 2.3-metre telescope at the Siding Spring Observatory in Australia. Discovering that it was the most luminous quasar ever observed, however, required a larger telescope and measurements from a more precise instrument. The X-shooter spectrograph on ESO’s VLT in the Chilean Atacama Desert provided the crucial data.

The fastest-growing black hole ever observed will also be a perfect target for the GRAVITY+ upgrade on ESO’s VLT Interferometer (VLTI), which is designed to accurately measure the mass of black holes, including those far away from Earth. Additionally, ESO’s Extremely Large Telescope (ELT), a 39-metre telescope under construction in the Chilean Atacama Desert, will make identifying and characterising such elusive objects even more feasible.

Finding and studying distant supermassive black holes could shed light on some of the mysteries of the early Universe, including how they and their host galaxies formed and evolved. But that’s not the only reason why Wolf searches for them.

“Personally, I simply like the chase,” he says. “For a few minutes a day, I get to feel like a child again, playing treasure hunt, and now I bring everything to the table that I have learned since.”

Heavy-element production in a compact object merger observed by JWST

by Andrew J. Levan, Benjamin P. Gompertz, Om Sharan Salafia, et al in Nature

An international team of astronomers — including Clemson University astrophysicist Dieter Hartmann — obtained observational evidence for the creation of rare heavy elements in the aftermath of a cataclysmic explosion triggered by the merger of two neutron stars.

The massive explosion unleashed a gamma-ray burst, GRB230307A, the second brightest in 50 years of observations and about 1,000 times brighter than a typical gamma-ray burst. GRB230307A was first detected by NASA’s Fermi Gamma-Ray Space Telescope on March 7, 2023.

Using multiple space- and ground-based telescopes, including NASA’s James Webb Space Telescope, the largest and most powerful telescope ever launched into space, scientists were able to pinpoint the source of the gamma-ray burst in the sky and track how its brightness changed. With the information gathered, the researchers determined the burst was the result of two neutron stars that merged in a galaxy 1 billion light-years from Earth to form a kilonova. The researchers observed evidence of tellurium, one of the rarest elements on Earth. The breakthrough discovery puts astronomers one step closer to solving the mystery of the origin of elements that are heavier than iron.

“I’m a high energy astrophysicist. I like explosions. I like the gamma rays that come from them. But I’m also an astronomer who really cares about fundamental questions like how did heavy elements form,” Hartmann said.

JWST images of GRB 230307A at 28.5 days post burst.

Gamma-ray bursts (GRBs) are bursts of gamma-ray light — the most energetic form of light — that last anywhere from seconds to minutes. The first GRBs were detected in the 1960s by satellites built to monitor nuclear testing. GRBs have different causes. Long duration GRBs are caused by supernovas, the point when a massive star reaches the end of its life and explodes into a burst of light. Short duration GRBs are caused by the merger of two neutron stars, known as a kilonova, or the merger of a neutron star and a black hole. Although GRB230307A lasted for 200 seconds, scientists saw the afterglow color change from blue to red, a signature of kilonova.

“The burst itself actually indicated a long duration event, and it should have been a normal supernova-type situation. But it had unusual features. It didn’t quite fit the patterns of long bursts,” Hartmann said. “It turns out that this radioactive cloud, that kilonova afterglow, which had all these nuclear synthetic fingerprints in it, is the signature of a binary merger. The excitement comes from using the Webb to identify a chemical fingerprint that we had expected for short bursts and seeing it inside a long burst.”

Hartmann said the Big Bang produced hydrogen and helium. All other elements were made by stars and processes in the interstellar medium.

“Some of them are massive enough to explode and they return that material to their gaseous environments which later make new stars. So, there’s a cycle in the universe that makes us more enriched in carbon, nitrogen, oxygen, all the things we need,” he said. “We call stars the cauldrons of the universe.”

Thermonuclear reactions, or fusion, make stars shine. That leads successively to the production of more heavy elements, Hartmann said. But when it gets to iron, there isn’t much energy left to squeeze out, he said. So, where do all the heavy elements such as gold and uranium come from?

“The heavy elements have special origins. There are two processes that dominate. One is called rapid; the other is called slow. We believe the r-process happens in those neutron star mergers,” Hartmann said.

Theoretical modeling suggested kilonovas should produce tellurium, but the detection of a spectral line by the James Webb Space Telescope provided experimental evidence. A spectral line is a dark or bright line within a continuous spectrum. It is produced by transitions within atoms or ions.

“We think it’s a pretty secure identification, but it’s not beyond a reasonable doubt like they would say in court,” Hartmann said.

Verification of a virtual lunar regolith simulant

by Joe Louca, John Vrublevskis, Kerstin Eder, Antonia Tzemanaki in Frontiers in Space Technologies

A new computer model mimics Moon dust so well that it could lead to smoother and safer Lunar robot teleoperations. The tool, developed by researchers at the University of Bristol and based at the Bristol Robotics Laboratory, could be used to train astronauts ahead of Lunar missions.

Working with their industry partner, Thales Alenia Space in the UK, who has specific interest in creating working robotic systems for space applications, the team investigated a virtual version of regolith, another name for Moon dust.

Lunar regolith is of particular interest for the upcoming Lunar exploration missions planned over the next decade. From it, scientists can potentially extract valuable resources such as oxygen, rocket fuel or construction materials, to support a long-term presence on the Moon.

To collect regolith, remotely operated robots emerge as a practical choice due to their lower risks and costs compared to human spaceflight. However, operating robots over these large distances introduces large delays into the system, which make them more difficult to control.

Identification of nearby particles in neighbouring cells. The world is divided into cubic cells. For a given particle (yellow), neighbouring particles (green) are identified as those in cells that share a face, edge, or corner, with the original particle. These neighbouring particles are checked for collisions, whereas particles in cells outside of this range (red) are ignored.

Now that the team know this simulation behaves similarly to reality, they can use it to mirror operating a robot on the Moon. This approach allows operators to control the robot without delays, providing a smoother and more efficient experience.

Lead author Joe Louca, based in Bristol’s School of Engineering Mathematics and Technology explained: “Think of it like a realistic video game set on the Moon — we want to make sure the virtual version of moon dust behaves just like the actual thing, so that if we are using it to control a robot on the Moon, then it will behave as we expect. “This model is accurate, scalable, and lightweight, so can be used to support upcoming lunar exploration missions.”

This study followed from previous work of the team, which found that expert robot operators want to train on their systems with gradually increasing risk and realism. That means starting in a simulation and building up to using physical mock-ups, before moving on to using the actual system. An accurate simulation model is crucial for training and developing the operator’s trust in the system.

While some especially accurate models of Moon dust had previously been developed, these are so detailed that they require a lot of computational time, making them too slow to control a robot smoothly. Researchers from DLR (German Aerospace Centre) tackled this challenge by developing a virtual model of regolith that considers its density, stickiness, and friction, as well as the Moon’s reduced gravity. Their model is of interest for the space industry as it is light on computational resources, and, hence, can be run in real-time. However, it works best with small quantities of Moon dust.

The Bristol team’s aims were to, firstly, extend the model so it can handle more regolith, while staying lightweight enough to run in real-time, and then to verify it experimentally.

Joe Louca added: “Our primary focus throughout this project was on enhancing the user experience for operators of these systems — how could we make their job easier? “We began with the original virtual regolith model developed by DLR, and modified it to make it more scalable.
“Then, we conducted a series of experiments — half in a simulated environment, half in the real world — to measure whether the virtual moon dust behaved the same as its real-world counterpart.”

As this model of regolith is promising for being accurate, scalable and lightweight enough to be used in real-time, the team will next investigate whether it can be used when operating robots to collect regolith. They also plan to investigate whether a similar system could be developed to simulate Martian soil, which could be of benefit for future exploration missions, or to train scientists to handle material from the highly anticipated Mars Sample Return mission.

Clouds and Clarity: Revisiting Atmospheric Feature Trends in Neptune-size Exoplanets

by Jonathan Brande, Ian J. M. Crossfield, Laura Kreidberg, Caroline V. Morley, Travis Barman, Björn Benneke, Jessie L. Christiansen, Diana Dragomir, Jonathan J. Fortney, Thomas P. Greene, Kevin K. Hardegree-Ullman, Andrew W. Howard, Heather A. Knutson, Joshua D. Lothringer, Thomas Mikal-Evans in The Astrophysical Journal Letters

The study of “exoplanets,” the sci-fi-sounding name for all planets in the cosmos beyond our own solar system, is a pretty new field. Mainly, exoplanet researchers like those in the ExoLab at the University of Kansas use data from space-borne telescopes such as the Hubble Space Telescope and Webb Space Telescope. Whenever news headlines offer findings of “Earth-like” planets or planets with the potential to support humanity, they’re talking about exoplanets within our own Milky Way.

Jonathan Brande, a doctoral candidate in the ExoLab at the University of Kansas, has just published findings showing new atmospheric detail in a set of 15 exoplanets similar to Neptune. While none could support humanity, a better understanding of their behavior might help us to understand why we don’t have a small Neptune, while most solar systems seem to feature a planet of this class.

“Over the past several years at KU, my focus has been studying the atmospheres of exoplanets through a technique known as transmission spectroscopy,” Brande said. “When a planet transits, meaning it moves between our line of sight and the star it orbits, light from the star passes through the planet’s atmosphere, getting absorbed by the various gases present. By capturing a spectrum of the star — passing the light through an instrument called a spectrograph, akin to passing it through a prism — we observe a rainbow, measuring the brightness of different constituent colors. Varied areas of brightness or dimness in the spectrum reveal the gases absorbing light in the planet’s atmosphere.”

With this methodology, several years ago Brande published a paper concerning the “warm Neptune” exoplanet TOI-674 b, where he presented observations indicating the presence of water vapor in its atmosphere. These observations were part of a broader program led by Brande’s adviser, Ian Crossfield, associate professor of physics & astronomy at KU, to observe atmospheres of Neptune-sized exoplanets.

“We want to comprehend the behaviors of these planets, given that those slightly larger than Earth and smaller than Neptune are the most common in the galaxy,” Brande said.

This recent ApJL paper summarizes observations from that program, incorporating data from additional observations to address why some planets appear cloudy while others are clear.

“The goal is to explore the physical explanations behind the distinct appearances of these planets,” Brande said.

Brande and his co-authors took special note of regions where exoplanets tend to form clouds or hazes high up in their atmosphere. When such atmospheric aerosols are present, the KU researcher said hazes can block the light filtering through the atmosphere.

“If a planet has a cloud right above the surface with hundreds of kilometers of clear air above it, starlight can easily pass through the clear air and be absorbed only by the specific gases in that part of the atmosphere,” Brande said. “However, if the cloud is positioned very high, clouds are generally opaque across the electromagnetic spectrum. While hazes have spectral features, for our work, where we focus on a relatively narrow range with Hubble, they also produce mostly flat spectra.”

Retrieved spectral feature amplitude, AH , compared to clear, cloudy, and hazy atmosphere models from Morley et al. (2015). For the clear and cloudy models, the dotted lines indicate a 100 × solar metallicity atmosphere, and the dashed lines a 300 × solar atmosphere.

According to Brande, when these aerosols are present high in the atmosphere, there’s no clear path for light to filter through.

“With Hubble, the single gas we’re most sensitive to is water vapor,” he said. “If we observe water vapor in a planet’s atmosphere, that’s a good indication that there are no clouds high enough to block its absorption. Conversely, if water vapor is not observed and only a flat spectrum is seen, despite knowing that the planet should have an extended atmosphere, it suggests the likely presence of clouds or hazes at higher altitudes.”

Brande led the work of an international team of astronomers on the paper, including Crossfield at KU and collaborators from the Max Planck Institute in Heidelberg, Germany, a cohort led by Laura Kreidberg, and investigators at the University of Texas, Austin, led by Caroline Morley. Brande and his co-authors approached their analysis differently than previous efforts by focusing on determining the physical parameters of the small-Neptune atmospheres. In contrast, previous analyses often involved fitting a single model spectrum to observations.

“Typically, researchers would take an atmospheric model with pre-computed water content, scale and shift it to match observed planets in their sample,” Brande said. “This approach indicates whether the spectrum is clear or cloudy but provides no information about the amount of water vapor or the location of clouds in the atmosphere.”

Instead, Brande employed a technique known as “atmospheric retrieval.”

“This involved modeling the atmosphere across various planet parameters such as water vapor quantity and cloud location, iterating through hundreds and thousands of simulations to find the best fit configuration,” he said. “Our retrievals gave us a best-fit model spectrum for each planet, from which we calculated how cloudy or clear the planet appeared to be. Then, we compared those measured clarities to a separate suite of models by Caroline Morley, which let us see that our results are in line with expectations for similar planets. In examining cloud and haze behavior, our models indicated that clouds were a better fit than hazes. The sedimentation efficiency parameter, reflecting cloud compactness, suggested observed planets had relatively low sedimentation efficiencies, resulting in fluffy clouds. These clouds, made up of particles like water droplets, remained lofted in the atmosphere due to their low settling tendency.”

The JWST Resolved Stellar Populations Early Release Science Program. IV. The Star Formation History of the Local Group Galaxy WLM

by Kristen. B. W. McQuinn, Max J. B. Newman, Alessandro Savino, et al in The Astrophysical Journal

Employing massive data sets collected through NASA’s James Webb Space Telescope, a research team led by a Rutgers University-New Brunswick astronomer is unearthing clues to conditions existing in the early universe.

The team has catalogued the ages of stars in the Wolf-Lundmark-Melotte (WLM) galaxy, constructing the most detailed picture of it yet, according to the researchers. WLM, a neighbor of the Milky Way, is an active center of star formation that includes ancient stars formed 13 billion years ago.

“In looking so deeply and seeing so clearly, we’ve been able to, effectively, go back in time,” said Kristen McQuinn, an assistant professor in the Department of Physics and Astronomy in the School of Arts and Sciences, who led the research”You’re basically going on a kind of archaeological dig, to find the very low mass stars that were formed early in the history of the universe.”

McQuinn credited the Amarel high performance computing cluster managed by the Rutgers Office of Advanced Research Computing for enabling the team to calculate the galaxy’s history of stellar development. One aspect of the research involved taking one massive calculation and repeating it 600 times, McQuinn said.

Ground-based optical image of WLM (image credit: ESO, VST/Omegacam Local Group Survey) with footprints of the NIRCam (solid), NIRISS (dotted), HST ACS (dashed), and HST WFC3/UVIS (dashed−dotted) fields overlaid.

The major computation effort also helped confirm telescope calibrations and data processing procedures that will benefit the wider scientific community, she added. So-called “low mass” galaxies are of special interest to McQuinn. Because they are believed to have dominated the early universe, they allow researchers to study the formation of stars, the evolution of chemical elements and the impact of star formation on the gas and structure of a galaxy. Faint and spread across the sky, they constitute the majority of galaxies in the local universe. Advanced telescopes such as the Webb are allowing scientists a closer look.

WLM — an “irregular” galaxy, meaning it doesn’t possess a distinct shape, such as a spiral or ellipse — was discovered by the German astronomer Max Wolf in 1909 and characterized in greater detail in 1926 by Swedish astronomer Knut Lundmark and British astronomer Philibert Jacques Melotte. It is positioned at the outskirts of the Local Group, a dumbbell-shaped group of galaxies that includes the Milky Way. Being at the edge of the Local Group has protected WLM from the ravages of intermingling with other galaxies, leaving its star population in a pristine state and useful for study, McQuinn noted. WLM also is interesting to astronomers because it is a dynamic, complex system with lots of gas, enabling it to actively form stars.

To formulate the galaxy’s star formation history — the rate at which stars have been born across different epochs of time in the universe — McQuinn and her team employed the telescope to painstakingly zero in on swaths of sky containing hundreds of thousands of individual stars. To determine the age of a star, they measured its color — a proxy for temperature — and its brightness.

“We can use what we know about stellar evolution and what these colors and brightnesses indicate to basically age the galaxy’s stars,” said McQuinn, adding the researchers then counted the stars of different ages and mapped out the birth rate of stars over the history of the universe. “What you end up with is a sense of how old this structure is that you’re looking at.”

Cataloging the stars in this way showed the researchers that WLM’s star producing abilities ebbed and flowed over time. The team’s observations, which confirm earlier assessments by scientists using the Hubble Space Telescope, show that the galaxy produced stars early in the history of the universe over a period of 3 billion years. It paused for a while, then re-ignited. McQuinn said she believes that the pause was caused by conditions specific to the early universe.

“The universe back then was really hot,” she said. “We think the temperature of the universe ended up heating the gas in this galaxy, and kind of turned off star formation for a while. The cool down period lasted a few billion years and then star formation proceeded again.”

The research is part of NASA’s Early Release Program, where designated scientists work with the Space Telescope Science Institute and conduct research designed to highlight Webb’s capabilities and help astronomers prepare for future observations.