ST/ Astronomers confirm star wreck as a source of extreme cosmic particles

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Paradigm

35 min readAug 17, 2022

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Space biweekly vol.58, 3d August — 17th August

TL;DR

Astronomers have long sought the launch sites for some of the highest-energy protons in our galaxy. Now a study using 12 years of data from NASA’s Fermi Gamma-ray Space Telescope confirms that one supernova remnant is just such a place.
The star Betelgeuse appears as a brilliant, ruby-red, twinkling spot of light in the upper right shoulder of the winter constellation Orion the Hunter. But when viewed close up, astronomers know it as a seething monster with a 400-day-long heartbeat of regular pulsations. This aging star is classified as a supergiant because it has swelled up to an astonishing diameter of approximately 1 billion miles. If placed at the center of our solar system it would reach out to the orbit of Jupiter. The star’s ultimate fate is to explode as a supernova.
Researchers are exploring ways to use clay-like topsoil materials from the moon or Mars as the basis for extraterrestrial cement that could be used by astronauts to create building materials for life in outer space. Scientists have converted simulated lunar and Martian soils into geopolymer cement, which is considered a good substitute for conventional cement.
Scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) to study planet formation have made the first-ever detection of gas in a circumplanetary disk. What’s more, the detection also suggests the presence of a very young exoplanet.
Researchers discover the first definitive proof that the Moon inherited indigenous noble gases from the Earth’s mantle. The discovery represents a significant piece of the puzzle towards understanding how the Moon and, potentially, the Earth and other celestial bodies were formed.
When humans, animals, and machines move throughout the world, they always push against something, whether it’s the ground, air, or water. Until recently, physicists believed this to be a constant, following the law of conservation momentum. Now, researchers from the Georgia Institute of Technology have proven the opposite — when bodies exist in curved spaces, it turns out that they can in fact move without pushing against something.
According to the standard model of cosmology, the vast majority of galaxies are surrounded by a halo of dark matter particles. This halo is invisible, but its mass exerts a strong gravitational pull on galaxies in the vicinity. A new study challenges this view of the Universe. The results suggest that the dwarf galaxies of Earth’s second closest galaxy cluster — known as the Fornax Cluster — are free of such dark matter halos.
New images from NASA’s James Webb Space Telescope show what may be among the earliest galaxies ever observed. The images were taken from the Cosmic Evolution Early Release Science Survey (CEERS).
Scientists have recorded millimeter-wavelength light from a fiery explosion caused by the merger of a neutron star with another star. The team also confirmed this flash of light to be one of the most energetic short-duration gamma-ray bursts ever observed, leaving behind one of the most luminous afterglows on record.
NASA’s James Webb Space Telescope has peered into the chaos of the Cartwheel Galaxy, revealing new details about star formation and the galaxy’s central black hole.
Upcoming industry events. And more!

Space industry in numbers

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

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

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

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Evidence for PeV Proton Acceleration from Fermi-LAT Observations of SNR G106.3+2.7

by Ke Fang, Matthew Kerr, Roger Blandford, Henrike Fleischhack, Eric Charles in Physical Review Letters

Astronomers have long sought the launch sites for some of the highest-energy protons in our galaxy. Now a study using 12 years of data from NASA’s Fermi Gamma-ray Space Telescope confirms that one supernova remnant is just such a place.

Fermi has shown that the shock waves of exploded stars boost particles to speeds comparable to that of light. Called cosmic rays, these particles mostly take the form of protons, but can include atomic nuclei and electrons. Because they all carry an electric charge, their paths become scrambled as they whisk through our galaxy’s magnetic field. Since we can no longer tell which direction they originated from, this masks their birthplace. But when these particles collide with interstellar gas near the supernova remnant, they produce a tell-tale glow in gamma rays — the highest-energy light there is.

“Theorists think the highest-energy cosmic ray protons in the Milky Way reach a million billion electron volts, or PeV energies,” said Ke Fang, an assistant professor of physics at the University of Wisconsin, Madison. “The precise nature of their sources, which we call PeVatrons, has been difficult to pin down.”

Trapped by chaotic magnetic fields, the particles repeatedly cross the supernova’s shock wave, gaining speed and energy with each passage. Eventually, the remnant can no longer hold them, and they zip off into interstellar space.

Boosted to some 10 times the energy mustered by the world’s most powerful particle accelerator, the Large Hadron Collider, PeV protons are on the cusp of escaping our galaxy altogether.

Astronomers have identified a few suspected PeVatrons, including one at the center of our galaxy. Naturally, supernova remnants top the list of candidates. Yet out of about 300 known remnants, only a few have been found to emit gamma rays with sufficiently high energies.

One particular star wreck has commanded a lot of attention from gamma-ray astronomers. Called G106.3+2.7, it’s a comet-shaped cloud located about 2,600 light-years away in the constellation Cepheus. A bright pulsar caps the northern end of the supernova remnant, and astronomers think both objects formed in the same explosion.

Fermi’s Large Area Telescope, its primary instrument, detected billion-electron-volt (GeV) gamma rays from within the remnant’s extended tail. (For comparison, visible light’s energy measures between about 2 and 3 electron volts.) The Very Energetic Radiation Imaging Telescope Array System (VERITAS) at the Fred Lawrence Whipple Observatory in southern Arizona recorded even higher-energy gamma rays from the same region. And both the High-Altitude Water Cherenkov Gamma-Ray Observatory in Mexico and the Tibet AS-Gamma Experiment in China have detected photons with energies of 100 trillion electron volts (TeV) from the area probed by Fermi and VERITAS.

“This object has been a source of considerable interest for a while now, but to crown it as a PeVatron, we have to prove it’s accelerating protons,” explained co-author Henrike Fleischhack at the Catholic University of America in Washington and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The catch is that electrons accelerated to a few hundred TeV can produce the same emission. Now, with the help of 12 years of Fermi data, we think we’ve made the case that G106.3+2.7 is indeed a PeVatron.”

The pulsar, J2229+6114, emits its own gamma rays in a lighthouse-like beacon as it spins, and this glow dominates the region to energies of a few GeV. Most of this emission occurs in the first half of the pulsar’s rotation. The team effectively turned off the pulsar by analyzing only gamma rays arriving from the latter part of the cycle. Below 10 GeV, there is no significant emission from the remnant’s tail.

Above this energy, the pulsar’s interference is negligible and the additional source becomes readily apparent. The team’s detailed analysis overwhelmingly favors PeV protons as the particles driving this gamma-ray emission.

“So far, G106.3+2.7 is unique, but it may turn out to be the brightest member of a new population of supernova remnants that emit gamma rays reaching TeV energies,” Fang notes. “More of them may be revealed through future observations by Fermi and very-high-energy gamma-ray observatories.”

The Great Dimming of Betelgeuse: a Surface Mass Ejection (SME) and its Consequences

by Andrea K. Dupree, Klaus G. Strassmeier, Thomas Calderwood, Thomas Granzer, Michael Weber , Kateryna Kravchenko, Lynn D. Matthews, Miguel Montarges, James Tappin, William T. Thompson in The Astrophysical Journal

The star Betelgeuse appears as a brilliant, ruby-red, twinkling spot of light in the upper right shoulder of the winter constellation Orion the Hunter. But when viewed close up, astronomers know it as a seething monster with a 400-day-long heartbeat of regular pulsations. This aging star is classified as a supergiant because it has swelled up to an astonishing diameter of approximately 1 billion miles. If placed at the center of our solar system it would reach out to the orbit of Jupiter. The star’s ultimate fate is to explode as a supernova. When that eventually happens it will be briefly visible in the daytime sky from Earth. But there are a lot of fireworks going on now before the final detonation.

Astronomers using Hubble and other telescopes have deduced that the star blew off a huge piece of its visible surface in 2019.

This has never before been seen on a star. Our petulant Sun routinely goes through mass ejections of its outer atmosphere, the corona. But those events are orders of magnitude weaker than what was seen on Betelgeuse. The first clue came when the star mysteriously darkened in late 2019. An immense cloud of obscuring dust formed from the ejected surface as it cooled. Astronomers have now pieced together a scenario for the upheaval. And the star is still slowly recovering; the photosphere is rebuilding itself. And the interior is reverberating like a bell that has been hit with a sledgehammer, disrupting the star’s normal cycle. This doesn’t mean the monster star is going to explode any time soon, but the late-life convulsions may continue to amaze astronomers.

Analyzing data from NASA’s Hubble Space Telescope and several other observatories, astronomers have concluded that the bright red supergiant star Betelgeuse quite literally blew its top in 2019, losing a substantial part of its visible surface and producing a gigantic Surface Mass Ejection (SME). This is something never before seen in a normal star’s behavior.

Our Sun routinely blows off parts of its tenuous outer atmosphere, the corona, in an event known as a Coronal Mass Ejection (CME). But the Betelgeuse SME blasted off 400 billion times as much mass as a typical CME!

The monster star is still slowly recovering from this catastrophic upheaval.

“Betelgeuse continues doing some very unusual things right now; the interior is sort of bouncing,” said Andrea Dupree of the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts.

These new observations yield clues as to how red stars lose mass late in their lives as their nuclear fusion furnaces burn out, before exploding as supernovae. The amount of mass loss significantly affects their fate. However, Betelgeuse’s surprisingly petulant behavior is not evidence the star is about to blow up anytime soon. So the mass loss event is not necessarily the signal of an imminent explosion.

Dupree is now pulling together all the puzzle pieces of the star’s petulant behavior before, after, and during the eruption into a coherent story of a never-before-seen titanic convulsion in an aging star.

This includes new spectroscopic and imaging data from the STELLA robotic observatory, the Fred L. Whipple Observatory’s Tillinghast Reflector Echelle Spectrograph (TRES), NASA’s Solar Terrestrial Relations Observatory spacecraft (STEREO-A), NASA’s Hubble Space Telescope, and the American Association of Variable Star Observers (AAVSO). Dupree emphasizes that the Hubble data was pivotal to helping sort out the mystery.

“We’ve never before seen a huge mass ejection of the surface of a star. We are left with something going on that we don’t completely understand. It’s a totally new phenomenon that we can observe directly and resolve surface details with Hubble. We’re watching stellar evolution in real time.”

The titanic outburst in 2019 was possibly caused by a convective plume, more than a million miles across, bubbling up from deep inside the star. It produced shocks and pulsations that blasted off the chunk of the photosphere leaving the star with a large cool surface area under the dust cloud that was produced by the cooling piece of photosphere. Betelgeuse is now struggling to recover from this injury.

Weighing roughly several times as much as our Moon, the fractured piece of photosphere sped off into space and cooled to form a dust cloud that blocked light from the star as seen by Earth observers. The dimming, which began in late 2019 and lasted for a few months, was easily noticeable even by backyard observers watching the star change brightness. One of the brightest stars in the sky, Betelgeuse is easily found in the right shoulder of the constellation Orion.

Even more fantastic, the supergiant’s 400-day pulsation rate is now gone, perhaps at least temporarily. For almost 200 years astronomers have measured this rhythm as evident in changes in Betelgeuse’s brightness variations and surface motions. Its disruption attests to the ferocity of the blowout.

The star’s interior convection cells, which drive the regular pulsation may be sloshing around like an imbalanced washing machine tub, Dupree suggests. TRES and Hubble spectra imply that the outer layers may be back to normal, but the surface is still bouncing like a plate of gelatin dessert as the photosphere rebuilds itself.

Though our Sun has coronal mass ejections that blow off small pieces of the outer atmosphere, astronomers have never witnessed such a large amount of a star’s visible surface get blasted into space. Therefore, surface mass ejections and coronal mass ejections may be different events.

Betelgeuse is now so huge now that if it replaced the Sun at the center of our solar system, its outer surface would extend past the orbit of Jupiter. Dupree used Hubble to resolve hot spots on the star’s surface in 1996. This was the first direct image of a star other than the Sun.

NASA’s Webb Space Telescope may be able to detect the ejected material in infrared light as it continues moving away from the star.

Comparison of lunar and Martian regolith simulant-based geopolymer cements formed by alkali-activation for in-situ resource utilization

by Jennifer N. Mills, Maria Katzarova, Norman J. Wagner in Advances in Space Research

Sustained space exploration will require infrastructure that doesn’t currently exist: buildings, housing, rocket landing pads.

So, where do you turn for construction materials when they are too big to fit in your carry-on and there’s no Home Depot in outer space?

Visual comparison of lunar and Martian simulants. (A) BP-1 Black Point lunar simulant; (B) JSC-1A Johnson Space Center lunar simulant; © LHS-1 Exolith Lab lunar highlands simulant; D) MGS-1 Exolith Lab Mars global simulant; (E) MGS-1C Exolith Lab Mars global simulant enriched with hydrated clay minerals (smectite).

“If we’re going to live and work on another planet like Mars or the moon, we need to make concrete. But we can’t take bags of concrete with us — we need to use local resources,” said Norman Wagner, Unidel Robert L. Pigford Chair of Chemical and Biomolecular Engineering at the University of Delaware.

Researchers are exploring ways to use clay-like topsoil materials from the moon or Mars as the basis for extraterrestrial cement. To succeed will require a binder to glue the extraterrestrial starting materials together through chemistry. One requirement for this out-of-this-world construction material is that it must be durable enough for the vertical launch pads needed to protect human-made rockets from swirling rocks, dust and other debris during liftoff or landing. Most conventional construction materials, such as ordinary cement, are not suitable under space conditions.

UD’s Wagner and colleagues are working on this problem and successfully converted simulated lunar and Martian soils into geopolymer cement, which is considered a good substitute for conventional cement. The research team also created a framework to compare different types of geopolymer cements and their characteristics and reported the results in Advances in Space Research.

Geopolymers are inorganic polymers formed from aluminosilicate minerals found in common clays everywhere from Newark, Delaware’s White Clay Creek to Africa. When mixed with a solvent that has a high pH, such as sodium silicate, the clay can be dissolved, freeing the aluminum and silicon inside to react with other materials and form new structures — like cement.

Soils on the moon and Mars contain common clays, too.

This made Maria Katzarova, a former associate scientist and member of Wagner’s lab at UD, wonder if it was possible to activate simulated moon and Martian soils to become concrete-like building materials using geopolymer chemistry. She proposed the idea to NASA and obtained funding via the Delaware Space Grant Consortium to try with the help and expertise of then-UD doctoral student Jennifer Mills, who studied terrestrial geopolymers for her doctoral dissertation. The researchers systematically prepared geopolymer binders from a variety of known simulated soils in the same exact way and compared the materials’ performance, which hadn’t been done before.

“This is not a trivial thing. You can’t just say give me any old clay, and I’ll make it work. There are metrics to it, chemistry that you have to worry about,” Wagner said.

The researchers mixed various simulated soils with sodium silicate then cast the geopolymer mixture into ice-cube-like molds and waited for the reaction to occur. After seven days, they measured each cube’s size and weight, then crushed it to understand how the material behaves under load. Specifically, they wanted to know if slight differences in chemistry between simulated soils affected the material’s strength.

“When a rocket takes off there’s a lot of weight pushing down on the landing pad and the concrete needs to hold, so the material’s compressive strength becomes an important metric,” Wagner said. “At least on Earth, we were able to make materials in little cubes that had the compressive strength necessary to do the job.”

The researchers also calculated how much terrestrial material astronauts would need to take with them to build a landing pad on the surface of the moon or Mars. Turns out, the estimated amount is well within the payload range of a rocket, anywhere from hundreds to thousands of kilograms.

The research team also subjected the samples to different environments present in space, including vacuum and low and high temperatures. What they found was informative.

Under vacuum, some of the material samples did form cement, while others were only partially successful. However, overall, the geopolymer cement’s compressive strength decreased under vacuum, compared to geopolymer cubes cured at room temperature and pressure. This raises new considerations depending on the material’s purpose.

“There’s going to be a tradeoff between whether we need to cast these materials in a pressurized environment to ensure the reaction forms the strongest material or whether can we get away with forming them under vacuum, the normal environment on the moon or Mars, and achieve something that’s good enough,” said Mills, who earned her doctoral degree in chemical engineering at UD in May 2022 and now works at Dow Chemical Company.

Meanwhile, under low temperatures of about -80 degrees Celsius, the geopolymer materials didn’t react at all.

“This tells us that we might need to use some sort of accelerant to achieve the strength we see at room temperature,” Mills said. “Maybe the geopolymer needs to be heated, or maybe we need to add something else to the mix to kickstart the reaction for certain applications or environments.”

At high temperatures, about 600 degrees Celsius, the researchers found that every moon-like sample got stronger. This was not surprising, Mills said, given how the kinetics were hindered at low temperatures. The research team also saw changes in the physical nature of the geopolymer cement under heat.

“The geopolymer bricks became much more brittle when we heated them up, shattering as opposed to becoming compressed or breaking in two,” Mills said. “That could be important if the material is going to be subjected to any type of external pressure.”

Based on their results, the researchers said that chemical composition and particle size may play an important role in material strength. For example, smaller particles increase the available surface area, making them easier to react and potentially leading to greater overall material strength. Another possible factor: the amount of aluminosilicate content in the starting materials, which can be tricky to estimate when added solutions may also contain small concentrations of these materials and contribute to material performance.

Well, Amazon doesn’t offer two-day delivery to space, so designing the right formulation of starting materials to take matters. Understanding what affects material strength is important, too, since astronauts will be sourcing our topsoil materials from different places on planets — and maybe even different planets altogether.

These results also can be used to make geopolymer cements on Earth that are better for the environment and can be sourced from a wider variety of local materials. Geopolymer cements require less water than is needed to make traditional cement, too, because the water itself is not consumed in the reaction. Instead, the water can be recovered and reused, a plus in water-limited environments from arid earthly landscapes to outer space.

Indigenous noble gases in the Moon’s interior

by Patrizia Will, Henner Busemann, My E. I. Riebe, Colin Maden in Science Advances

Humankind has maintained an enduring fascination with the Moon. It was not until Galileo’s time, however, that scientists really began study it. Over the course of nearly five centuries, researchers put forward numerous, much debated theories as to how the Moon was formed. Now, geochemists, cosmochemists, and petrologists at ETH Zurich shed new light on the Moon’s origin story. In a study just published in the journal, Science Advances, the research team reports findings that show that the Moon inherited the indigenous noble gases of helium and neon from Earth’s mantle. The discovery adds to the already strong constraints on the currently favoured “Giant Impact” theory that hypothesizes the Moon was formed by a massive collision between Earth and another celestial body.

During her doctoral research at ETH Zurich, Patrizia Will analysed six samples of lunar meteorites from an Antarctic collection, obtained from NASA. The meteorites consist of basalt rock that formed when magma welled up from the interior of the Moon and cooled quickly. They remained covered by additional basalt layers after their formation, which protected the rock from cosmic rays and, particularly, the solar wind. The cooling process resulted in the formation of lunar glass particles amongst the other minerals found in magma. Will and the team discovered that the glass particles retain the chemical fingerprints (isotopic signatures) of the solar gases: helium and neon from the Moon’s interior. Their findings strongly support that the Moon inherited noble gases indigenous to the Earth.

“Finding solar gases, for the first time, in basaltic materials from the Moon that are unrelated to any exposure on the lunar surface was such an exciting result,” says Will.

Without the protection of an atmosphere, asteroids continually pelt the Moon’s surface. It likely took a high-energy impact to eject the meteorites from the middle layers of the lava flow similar to the vast plains known as the Lunar Mare. Eventually the rock fragments made their way to Earth in the form of meteorites. Many of these meteorite samples are picked up in the deserts of North Africa or in, in this case, the “cold desert” of Antarctica where they are easier to spot in the landscape.

In the Noble Gas Laboratory at ETH Zurich resides a state-of-the-art noble gas mass spectrometer named, “Tom Dooley” — sung about in the Grateful Dead tune by the same name. The instrument got its name, when earlier researchers, at one point, suspended the highly sensitive equipment from the ceiling of the lab to avoid interference from the vibrations of everyday life. Using the Tom Dooley instrument, the research team was able to measure sub-millimetre glass particles from the meteorites and rule out solar wind as the source of the detected gases. The helium and neon that they detected were in a much higher abundance than expected.

The Tom Dooley is so sensitive that it is, in fact, the only instrument in the world capable of detecting such minimal concentrations of helium and neon. It was used to detect these noble gases in the 7 billion years old grains in the Murchison meteorite — the oldest known solid matter to-date.

Isotopic compositions of bulk samples, glasses, and mineral separates. (A) Neon three-isotope plot. L24 and L36 (two aliquots each) contain solar-type gases, dominantly Nesolar with admixture of Necos. L05 and L26 (two aliquots each) and L32 and L41 (one aliquot each) contain purely Necos. Black glasses (L24 and L36) carry the solar-type gases. Some maskelynite and opaque grains were contaminated by solar gas–bearing black glass (fig. S5, A and B). Gray dashed arrow, calculated mass-dependent solar wind (SW) fractionation; red line, linear fit through bulk data points, 20Ne/22Nesolar ~ 12.5. Inset: Black dashed arrow, mass-dependent SW fractionation; black solid arrow, 20Ne/22Nesolar ~ 13.1 in black glass. (B) 3He/4He versus 4He. Olivine, feldspar, and pyroxene have higher 3Hecos production rates than the opaque minerals. The opaque minerals are dominated by 4Herad. Solar-type He is dominant in black glass (L24 and L36), whereas black glass without dominant solar-type He shows similar 3He/4He as the opaque minerals due to additional 4Herad; 3He/4He is similar to SW-He (fig. S1 for details). © 38Ar/36Ar versus 40Ar/36Ar. All bulk samples contain similar concentrations of Arcos and 40Arrad (tables S3 and S9). L24 and L36 are dominated by additional Arsolar. Air-Ar is absent, consistent with He and Ne isotopes. (D) 126Xe/132Xe versus 136Xe/132Xe in bulk LAP basalts. Xenon in L24 is consistent with solar-type gases and fission Xe. A mixture of solar-type gases and Q, AVCC, air, or fission Xe is indicated for L36_2. L36_1 contains a higher Xecos concentration, while solar-type gases are not clearly indicated. Xenon in L05 and L26 is most likely air but could also be mixed SW and fission Xe. Admixture of fission Xe is visible in L32 and L41. References: SW (33, 69), cosmogenic (35), air (70–73), Q (28), and AVCC (29, 30). Error bars are mostly within symbols.

Knowing where to look inside NASA’s vast collection of some 70,000 approved meteorites represents a major step forward.

“I am strongly convinced that there will be a race to study heavy noble gases and isotopes in meteoritic materials,” says ETH Zurich Professor Henner Busemann, one of the world’s leading scientists in the field of extra-terrestrial noble gas geochemistry.

He anticipates that soon researchers will be looking for noble gases such as xenon and krypton which are more challenging to identify. They will also be searching for other volatile elements such as hydrogen or halogens in the lunar meteorites.

Busemann comments, “While such gases are not necessary for life, it would be interesting to know how some of these noble gases survived the brutal and violent formation of the moon. Such knowledge might help scientists in geochemistry and geophysics to create new models that show more generally how such most volatile elements can survive planet formation, in our solar system and beyond.”

Molecules with ALMA at Planet-forming Scales (MAPS): A Circumplanetary Disk Candidate in Molecular-line Emission in the AS 209 Disk

by Jaehan Bae, Richard Teague, Sean M. Andrews, Myriam Benisty, Stefano Facchini, Maria Galloway-Sprietsma, Ryan A. Loomis, Yuri Aikawa, Felipe Alarcón, Edwin Bergin, Jennifer B. Bergner, Alice S. Booth, Gianni Cataldi, L. Ilsedore Cleeves, Ian Czekala, Viviana V. Guzmán, Jane Huang, John D. Ilee, Nicolas T. Kurtovic, Charles J. Law, Romane Le Gal, Yao Liu, Feng Long, François Ménard, Karin I. Öberg, Laura M. Pérez, Chunhua Qi, Kamber R. Schwarz, Anibal Sierra, Catherine Walsh, David J. Wilner, Ke Zhang in The Astrophysical Journal Letters

Scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) — in which the National Radio Astronomy Observatory (NRAO) is a partner — to study planet formation have made the first-ever detection of gas in a circumplanetary disk. What’s more, the detection also suggests the presence of a very young exoplanet. The results of the research are published in The Astrophysical Journal Letters.

Circumplanetary disks are an amassing of gas, dust, and debris around young planets. These disks give rise to moons and other small, rocky objects, and control the growth of young, giant planets. Studying these disks in their earliest stages may help shed light on the formation of our own Solar System, including that of Jupiter’s Galilean moons, which scientists believe formed in a circumplanetary disk of Jupiter around 4.5 billion years ago.

While studying AS 209 — a young star located roughly 395 light-years from Earth in the constellation Ophiuchus — scientists observed a blob of emitted light in the middle of an otherwise empty gap in the gas surrounding the star. That led to the detection of the circumplanetary disk surrounding a potential Jupiter-mass planet. Scientists are watching the system closely, both because of the planet’s distance from its star and the star’s age. The exoplanet is located more than 200 astronomical units, or 18.59 billion miles, away from the host star, challenging currently accepted theories of planet formation. And if the host star’s estimated age of just 1.6 million years holds true, this exoplanet could be one of the youngest ever detected. Further study is needed, and scientists hope that upcoming observations with the James Webb Space Telescope will confirm the planet’s presence.

Selected 12CO J = 2−1 channel maps. The upper panels show an annular gap. The black dashed ellipses present the projected circular orbit with a radius of 206 au. Lower panels show a large velocity perturbation on the southern side of the disk (highlighted with black circles). A similar perturbation is not present on the northern side of the disk, emphasizing the localized nature of the perturbation. The synthesized beam is presented in the lower-left corner of each panel. The color map starts at 5σ ≃ 3.3 mJy beam−1.

“The best way to study planet formation is to observe planets while they’re forming. We are living in a very exciting time when this happens thanks to powerful telescopes, such as ALMA and JWST,” said Jaehan Bae, a professor of astronomy at the University of Florida and the lead author of the paper.

Scientists have long suspected the presence of circumplanetary disks around exoplanets, but until recently were unable to prove it. In 2019, ALMA scientists made the first-ever detection of a circumplanetary, moon-forming disk while observing the young exoplanet PDS 70c, and confirmed the find in 2021. The new observations of gas in a circumplanetary disk at AS 209 may shed further light on the development of planetary atmospheres and the processes by which moons are formed.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Robotic swimming in curved space via geometric phase

by Shengkai Li, Tianyu Wang, Velin H. Kojouharov, James McInerney, Enes Aydin, Yasemin Ozkan-Aydin, Daniel I. Goldman, D. Zeb Rocklin in Proceedings of the National Academy of Sciences

When humans, animals, and machines move throughout the world, they always push against something, whether it’s the ground, air, or water. Until recently, physicists believed this to be a constant, following the law of conservation momentum. Now, researchers from the Georgia Institute of Technology have proven the opposite — when bodies exist in curved spaces, it turns out that they can in fact move without pushing against something.

In the paper, a team of researchers led by Zeb Rocklin, assistant professor in the School of Physics at Georgia Tech, created a robot confined to a spherical surface with unprecedented levels of isolation from its environment, so that these curvature-induced effects would predominate.

Self-propulsion without reaction forces. (A) A robot confined to a spherical surface executes a cyclic change of shape to generate net position change. (B) The cyclic change of shape described by the angles θh,θv of motorized weights (black dots) follows an order indicated by the gait diagram in Lower. Due to the variable moment of inertia and the noncommutativity of these operations, this leads to a net change in the robot’s position, represented by the rotation ϕ(t) *applied to the coordinate axes in position space, even in the absence of momentum or external forces. The plot in Lower shows the time evolution of* ϕ(t) *from each stroke of the gait shown in the same color as the gait diagram.*

“We let our shape-changing object move on the simplest curved space, a sphere, to systematically study the motion in curved space,” said Rocklin. “We learned that the predicted effect, which was so counter-intuitive it was dismissed by some physicists, indeed occurred: as the robot changed its shape, it inched forward around the sphere in a way that could not be attributed to environmental interactions.”

The researchers set out to study how an object moved within a curved space. To confine the object on the sphere with minimal interaction or exchange of momentum with the environment in the curved space, they let a set of motors drive on curved tracks as moving masses. They then connected this system holistically to a rotating shaft so that the motors always move on a sphere. The shaft was supported by air bearings and bushings to minimize the friction, and the alignment of the shaft was adjusted with the Earth’s gravity to minimize the residual force of gravity.

From there, as the robot continued to move, gravity and friction exerted slight forces on it. These forces hybridized with the curvature effects to produce a strange dynamic with properties neither could induce on their own. The research provides an important demonstration of how curved spaces can be attained and how it fundamentally challenges physical laws and intuition designed for flat space. Rocklin hopes the experimental techniques developed will allow other researchers to explore these curved spaces.

While the effects are small, as robotics becomes increasingly precise, understanding this curvature-induced effect may be of practical importance, just as the slight frequency shift induced by gravity became crucial to allow GPS systems to accurately convey their positions to orbital satellites. Ultimately, the principles of how a space’s curvature can be harnessed for locomotion may allow spacecraft to navigate the highly curved space around a black hole.

“This research also relates to the ‘Impossible Engine’ study,” said Rocklin. “Its creator claimed that it could move forward without any propellant. That engine was indeed impossible, but because spacetime is very slightly curved, a device could actually move forward without any external forces or emitting a propellant — a novel discovery.”

The distribution and morphologies of Fornax Cluster dwarf galaxies suggest they lack dark matter

by Elena Asencio, Indranil Banik, Steffen Mieske, Aku Venhola, Pavel Kroupa, Hongsheng Zhao in Monthly Notices of the Royal Astronomical Society

Dwarf galaxies are small, faint galaxies that can usually be found in galaxy clusters or near larger galaxies. Because of this, they might be affected by the gravitational effects of their larger companions. “We introduce an innovative way of testing the standard model based on how much dwarf galaxies are disturbed by gravitational ,tides’ from nearby larger galaxies,” said Elena Asencio, a PhD student at the University of Bonn and the lead author of the story. Tides arise when gravity from one body pulls differently on different parts of another body. These are similar to tides on Earth, which arise because the moon pulls more strongly on the side of Earth which faces the moon.

The Fornax Cluster has a rich population of dwarf galaxies. Recent observations show that some of these dwarfs appear distorted, as if they have been perturbed by the cluster environment.

“Such perturbations in the Fornax dwarfs are not expected according to the Standard Model,” said Pavel Kroupa, Professor at the University of Bonn and Charles University in Prague. “This is because, according to the standard model, the dark matter halos of these dwarfs should partly shield them from tides raised by the cluster.”

The authors analyzed the expected level of disturbance of the dwarfs, which depends on their internal properties and their distance to the gravitationally powerful cluster center. Galaxies with large sizes but low stellar masses and galaxies close to the cluster centre are more easily disturbed or destroyed. They compared the results with their observed level of disturbance evident from photographs taken by the VLT Survey Telescope of the European Southern Observatory.

“The comparison showed that, if one wants to explain the observations in the standard model” — said Elena Asencio — “the Fornax dwarfs should already be destroyed by gravity from the cluster center even when the tides it raises on a dwarf are sixty-four times weaker than the dwarf’s own self-gravity.”

Not only is this counter-intuitive, she said, it also contradicts previous studies, which found that the external force needed to disturb a dwarf galaxy is about the same as the dwarf’s selfgravity.

From this, the authors concluded that, in the standard model, it is not possible to explain the observed morphologies of the Fornax dwarfs in a self-consistent way. They repeated the analysis using Milgromian dynamics (MOND). Instead of assuming dark matter halos surrounding galaxies, the MOND theory proposes a correction to Newtonian dynamics by which gravity experiences a boost in the regime of low accelerations.

“We were not sure that the dwarf galaxies would be able to survive the extreme environment of a galaxy cluster in MOND, due to the absence of protective dark matter halos in this model — admitted Dr Indranil Banik from the University of St Andrews — “but our results show a remarkable agreement between observations and the MOND expectations for the level of disturbance of the Fornax dwarfs.”

“It is exciting to see that the data we obtained with the VLT survey telescope allowed such a thorough test of cosmological models,” said Aku Venhola from the University of Oulu (Finland) and Steffen Mieske from the European Southern Observatory, co-authors of the study.

This is not the first time that a study testing the effect of dark matter on the dynamics and evolution of galaxies concluded that observations are better explained when they are not surrounded by dark matter. “The number of publications showing incompatibilities between observations and the dark matter paradigm just keeps increasing every year. It is time to start investing more resources into more promising theories,” said Pavel Kroupa, member of the Transdisciplinary Research Areas “Modelling” and “Matter” at the University of Bonn.

Dr. Hongsheng Zhao from the University of St Andrews added:

“Our results have major implications for fundamental physics. We expect to find more disturbed dwarfs in other clusters, a prediction which other teams should verify.”

A Long Time Ago in a Galaxy Far, Far Away: A Candidate z ~ 14 Galaxy in Early JWST CEERS Imaging

by Steven L. Finkelstein et al. submitted to arXiv

New images from NASA’s James Webb Space Telescope show what may be among the earliest galaxies ever observed. The images include objects from more than 13 billion years ago, and one offers a much wider field of view than Webb’s First Deep Field image, which was released July 12. The images represent some of the first out of a major collaboration of astronomers and other academic researchers teaming with NASA and global partners to uncover new insights about the universe.

The images were taken from the Cosmic Evolution Early Release Science Survey (CEERS), led by a scientist at The University of Texas at Austin. Jeyhan Kartaltepe, an associate professor from Rochester Institute of Technology’s School of Physics and Astronomy, is one of 18 co-investigators from 12 institutions along with more than 100 collaborators from the U.S. and nine other countries. CEERS researchers are studying how some of the earliest galaxies formed when the universe was less than 5 percent of its current age, during a period known as reionization, and how galaxies evolved between then and today.

The team has identified one particularly exciting object that they estimate is being observed as it was just 290 million years after the Big Bang. Astronomers refer to this as a redshift of z~14.

The finding has been published on the preprint server arXiv and is awaiting publication in a peer-reviewed journal. If the finding is confirmed, it would be one of the earliest galaxies ever observed, and its presence would indicate that galaxies started forming much earlier than many astronomers previously thought.

The unprecedentedly sharp images reveal a flurry of complex galaxies evolving over time — some elegantly mature pinwheels, others blobby toddlers, still others gauzy swirls of do-si-doing neighbors. The images, which took about 24 hours to collect, are from a patch of sky near the handle of the Big Dipper, a constellation formally named Ursa Major. This same area of sky was observed previously by the Hubble Space Telescope, as seen in the Extended Groth Strip.

“These images are exciting because the sheer number of these really high redshift galaxy candidates is larger than we expected,” said Kartaltepe. “We knew we’d find some, but I don’t think anybody thought we’d find as many as we have. It either means the universe works a little bit differently than we thought or there’s a lot of other contaminating sources and these candidates will turn out to be something else. The reality is probably a mix of both.”

Kartaltepe has multiple leading roles in the survey, focusing on morphology — measuring the shapes and sizes of galaxies and studying how their structures evolved — and setting up and analyzing spectroscopic observations of distant galaxies using the NIRSpec instrument. Three of her astrophysical sciences and technology Ph.D. students — Isabella Cox, Caitlin Rose, and Brittany Vanderhoof — have been involved in the survey and working with the data.

The entire CEERS program will involve more than 60 hours of telescope time. Much more imaging data will be collected in December, along with spectroscopic measurements of hundreds of distant galaxies.

Kartaltepe is also principal investigator of COSMOS-Web, the largest General Observer program selected for JWST’s first year. Over the course of 218 observing hours, COSMOS-Web will conduct an ambitious survey of half a million galaxies with multi-band, high-resolution near infrared imaging and an unprecedented 32,000 galaxies in mid infrared. JWST is expected to begin collecting the first data for COSMOS-Web in December.

The First Short GRB Millimeter Afterglow: The Wide-Angled Jet of the Extremely Energetic SGRB 211106A

by Laskar et al. in The Astrophysical Journal Letters

Scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) — an international observatory co-operated by the US National Science Foundation’s National Radio Astronomy Observatory (NRAO) — have for the first time recorded millimeter-wavelength light from a fiery explosion caused by the merger of a neutron star with another star. The team also confirmed this flash of light to be one of the most energetic short-duration gamma-ray bursts ever observed, leaving behind one of the most luminous afterglows on record.

Gamma-ray bursts (GRBs) are the brightest and most energetic explosions in the Universe, capable of emitting more energy in a matter of seconds than our Sun will emit during its entire lifetime. GRB 211106A belongs to a GRB sub-class known as short-duration gamma-ray bursts. These explosions — which scientists believe are responsible for the creation of the heaviest elements in the Universe, such as platinum and gold — result from the catastrophic merger of binary star systems containing a neutron star.

“These mergers occur because of gravitational wave radiation that removes energy from the orbit of the binary stars, causing the stars to spiral in toward each other,” said Tanmoy Laskar, who will soon commence work as an Assistant Professor of Physics and Astronomy at the University of Utah.
“The resulting explosion is accompanied by jets moving at close to the speed of light. When one of these jets is pointed at Earth, we observe a short pulse of gamma-ray radiation or a short-duration GRB.”

A short-duration GRB usually lasts only a few tenths of a second. Scientists then look for an afterglow, an emission of light caused by the interaction of the jets with surrounding gas. Even still, they’re difficult to detect; only half-a-dozen short-duration GRBs have been detected at radio wavelengths, and until now none had been detected in millimeter wavelengths. Laskar, who led the research while an Excellence Fellow at Radboud University in The Netherlands, said that the difficulty is the immense distance to GRBs, and the technological capabilities of telescopes.

“Short-duration GRB afterglows are very luminous and energetic. But these explosions take place in distant galaxies which means the light from them can be quite faint for our telescopes on Earth. Before ALMA, millimeter telescopes were not sensitive enough to detect these afterglows.”

Having occurred when the Universe was just 40-percent of its current age, GRB 211106A is no exception. The light from this short-duration gamma-ray burst was so faint that while early X-ray observations with NASA’s Neil Gehrels Swift Observatory saw the explosion, the host galaxy was undetectable at that wavelength, and scientists weren’t able to determine exactly where the explosion was coming from.

“Afterglow light is essential for figuring out which galaxy a burst comes from and for learning more about the burst itself. Initially, when only the X-ray counterpart had been discovered, astronomers thought that this burst might be coming from a nearby galaxy,” said Laskar, adding that a significant amount of dust in the area also obscured the object from detection in optical observations with the Hubble Space Telescope.

Each wavelength added a new dimension to scientists’ understanding of the GRB, and millimeter, in particular, was critical to uncovering the truth about the burst.

“The Hubble observations revealed an unchanging field of galaxies. ALMA’s unparalleled sensitivity allowed us to pinpoint the location of the GRB in that field with more precision, and it turned out to be in another faint galaxy, which is further away. That, in turn, means that this short-duration gamma-ray burst is even more powerful than we first thought, making it one of the most luminous and energetic on record,” said Laskar.

Wen-fai Fong, an Assistant Professor of Physics and Astronomy at Northwestern University added:

“This short gamma-ray burst was the first time we tried to observe such an event with ALMA. Afterglows for short bursts are very difficult to come by, so it was spectacular to catch this event shining so bright. After many years of observing these bursts, this surprising discovery opens up a new area of study, as it motivates us to observe many more of these with ALMA, and other telescope arrays, in the future.”

Joe Pesce, National Science Foundation Program Officer for NRAO/ALMA said:

“These observations are fantastic on many levels. They provide more information to help us understand the enigmatic gamma-ray bursts (and neutron-star astrophysics in general), and they demonstrate how important and complementary multi-wavelength observations with space- and ground-based telescopes are in understanding astrophysical phenomena.”

And there’s plenty of work still to be done across multiple wavelengths, both with new GRBs and with GRB 211106A, which could uncover additional surprises about these bursts.

“The study of short-duration GRBs requires the rapid coordination of telescopes around the world and in space, operating at all wavelengths,” said Edo Berger, Professor of Astronomy at Harvard University and researcher at the Center for Astrophysics | Harvard & Smithsonian. “In the case of GRB 211106A, we used some of the most powerful telescopes available — ALMA, the National Science Foundation’s Karl G. Jansky Very Large Array (VLA), NASA’s Chandra X-ray Observatory, and the Hubble Space Telescope. With the now-operational James Webb Space Telescope (JWST), and future 20–40 meter optical and radio telescopes such as the next generation VLA (ngVLA) we will be able to produce a complete picture of these cataclysmic events and study them at unprecedented distances.”

Laskar added:

“With JWST, we can now take a spectrum of the host galaxy and easily know the distance, and in the future, we could also use JWST to capture infrared afterglows and study their chemical composition. With ngVLA, we will be able to study the geometric structure of the afterglows and the star-forming fuel found in their host environments in unprecedented detail. I am excited about these upcoming discoveries in our field.”

Webb captures stellar gymnastics in the Cartwheel Galaxy

by NASA/Goddard Space Flight Center

NASA’s James Webb Space Telescope has peered into the chaos of the Cartwheel Galaxy, revealing new details about star formation and the galaxy’s central black hole. Webb’s powerful infrared gaze produced a detailed image of the Cartwheel and two smaller companion galaxies against a backdrop of many other galaxies. The image provides a new view of how the Cartwheel Galaxy has changed over billions of years.

The Cartwheel Galaxy, located about 500 million light-years away in the Sculptor constellation, is a rare sight. Its appearance, much like that of the wheel of a wagon, is the result of an intense event — a high-speed collision between a large spiral galaxy and a smaller galaxy not visible in this image. Collisions of galactic proportions cause a cascade of different, smaller events between the galaxies involved; the Cartwheel is no exception.

The collision most notably affected the galaxy’s shape and structure. The Cartwheel Galaxy sports two rings — a bright inner ring and a surrounding, colorful ring. These two rings expand outwards from the center of the collision, like ripples in a pond after a stone is tossed into it. Because of these distinctive features, astronomers call this a “ring galaxy,” a structure less common than spiral galaxies like our Milky Way.

The bright core contains a tremendous amount of hot dust with the brightest areas being the home to gigantic young star clusters. On the other hand, the outer ring, which has expanded for about 440 million years, is dominated by star formation and supernovas. As this ring expands, it plows into surrounding gas and triggers star formation.

Other telescopes, including the Hubble Space Telescope, have previously examined the Cartwheel. But the dramatic galaxy has been shrouded in mystery — perhaps literally, given the amount of dust that obscures the view. Webb, with its ability to detect infrared light, now uncovers new insights into the nature of the Cartwheel.

The Near-Infrared Camera (NIRCam), Webb’s primary imager, looks in the near-infrared range from 0.6 to 5 microns, seeing crucial wavelengths of light that can reveal even more stars than observed in visible light. This is because young stars, many of which are forming in the outer ring, are less obscured by the presence of dust when observed in infrared light. In this image, NIRCam data are colored blue, orange, and yellow. The galaxy displays many individual blue dots, which are individual stars or pockets of star formation. NIRCam also reveals the difference between the smooth distribution or shape of the older star populations and dense dust in the core compared to the clumpy shapes associated with the younger star populations outside of it.

Learning finer details about the dust that inhabits the galaxy, however, requires Webb’s Mid-Infrared Instrument (MIRI). MIRI data are colored red in this composite image. It reveals regions within the Cartwheel Galaxy rich in hydrocarbons and other chemical compounds, as well as silicate dust, like much of the dust on Earth. These regions form a series of spiraling spokes that essentially form the galaxy’s skeleton. These spokes are evident in previous Hubble observations released in 2018, but they become much more prominent in this Webb image.

Webb’s observations underscore that the Cartwheel is in a very transitory stage. The galaxy, which was presumably a normal spiral galaxy like the Milky Way before its collision, will continue to transform. While Webb gives us a snapshot of the current state of the Cartwheel, it also provides insight into what happened to this galaxy in the past and how it will evolve in the future.

The James Webb Space Telescope is the world’s premier space science observatory. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.