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hollow ice sphere

You’re looking at a frozen, hollow shell of ice roughly 20 cm in diameter and 3 cm thick. In a new laboratory study, scientists Kathryn Harriss and Mark Burchell (University of Kent, UK) have studied what happens when a shell like this is shot with a small, high-speed projectile, causing the ice shell to explode into pieces. You can watch a slow motion video of their experiment below!

This process simulates the possible high-speed collisions and catastrophic disruptions of icy bodies — like the frozen moons of Saturn and Jupiter — in the early solar system. By exploring how a hollow ice sphere responds to impact, Harriss and Burchell hope to better understand the relative roles of a body’s core and its surface layers in determining what happens during a catastrophic disruption. Which is more important in a collision: an icy object’s crust or its core? Check out the original article, linked below, for more information on what the authors learned.

Citation

“Catastrophic Disruption of Hollow Ice Spheres,” Kathryn H. Harriss and Mark J. Burchell 2020 Planet. Sci. J. 1 19. doi:10.3847/PSJ/ab8f34

atmospheric ion loss

Could TOI-700 d, an Earth-sized planet in the habitable zone of an early-type M-dwarf star, have held on to its atmosphere over long timescales? This question is crucial to understanding whether this recent discovery from the Transiting Exoplanet Survey Satellite (TESS) is likely to have a habitable surface. In a recent study led by Chuanfei Dong (Princeton University), a team of scientists conducted a series of state-of-the-art simulations to model the atmospheric escape from TOI-700 d as the planet is bombarded by its host’s stellar wind. The plots above show the O+ ion density and magnetic field lines in various cases from the authors’ simulations (see the original image for scales and additional detail). Though TOI-700 d’s atmospheric ion escape rates could be a few orders of magnitude higher than the rates typical of the terrestrial planets in our own solar system, the authors show that TOI-700 d could still retain a substantial atmosphere for more than a billion years — so it may well be worth exploring this planet further in the future! For more information, check out the full article below.

Citation

“Atmospheric Escape From TOI-700 d: Venus versus Earth Analogs,” Chuanfei Dong et al 2020 ApJL 896 L24. doi:10.3847/2041-8213/ab982f

Betelgeuse binary merger

This image from a simulation shows how the the large, red supergiant star Betelgeuse may have been created by the tidal disruption and merger of a binary star within the past few hundred thousand years. Betelgeuse — a prominent star in our night sky — has recently made headlines due to its unexpected, sudden dimming and rebrightening. But the supergiant has other quirks, like how it’s hurtling rapidly through space as a “runaway” star, or how it spins unusually fast for its size. A team of Louisiana State University researchers led by Manos Chatzopoulos has now performed simulations that show that Betelgeuse’s odd properties could be explained if the supergiant was formed by the merger of an unequal-mass binary star system in the relatively recent past. To learn more about the authors’ results, check out the original article below.

Betelgeuse merger full

The full view of two frames from one of the authors’ simulations. The left image shows the original configuration of the unequal-mass binary star system; the right image shows the tidal disruption of the secondary around the core of the primary. [Chatzopoulos et al. 2020]

Citation

“Is Betelgeuse the Outcome of a Past Merger?,” E. Chatzopoulos et al 2020 ApJ 896 50. doi:10.3847/2041-8205/820/2/L40

turbulent mixing layer simulation

What happens in galactic and intergalactic settings when cold, dense gas moves through hot, diffuse gas? You can see the result in the complex simulations shown above (click for a closer look), as reported in a recent publication led by scientist Drummond Fielding (Center for Computational Astrophysics, Flatiron Institute). Turbulent mixing layers like those simulated by Fielding and collaborators form in a vast variety of cosmic environments: the interstellar medium, the circumgalactic medium, expanding supernova remnants, cosmic filaments, galactic winds, protoplanetary disks, the solar corona, and many more. The authors’ new models show the fractal nature of the cooling surface that arises within these layers as the gases mix.

You can watch the animated version of the simulation below, which shows how eight different fluid properties evolve over time in a turbulent layer containing mixing cold and hot gas. For more information, check out the original article, linked below.

Citation

“Multiphase Gas and the Fractal Nature of Radiative Turbulent Mixing Layers,” Drummond B. Fielding et al 2020 ApJL 894 L24. doi:10.3847/2041-8213/ab8d2c

BUFFALO image of A370

Be sure to click on the above image and enlarge it for the full view of the stunning, rich galaxy cluster Abell 370 (top right) and its surrounding area. This image was captured as part of the Beyond Ultra-deep Frontier Fields and Legacy Observations (BUFFALO) program, which is using 101 orbits of Hubble Space Telescope time to revisit the six Hubble Frontier Fields galaxy clusters and their flanking regions. Expanding on the Frontier Fields study, each set of BUFFALO images covers a region that’s four times larger than the previous coverage — the red-shaded section above shows the area that was previously imaged through Frontier Fields. BUFFALO’s wide, deep look will take advantage of gravitational lensing from these massive galaxy clusters to do two things: discover distant, high-redshift galaxies that lie behind the clusters, and study dark matter and galaxy assembly using the foreground clusters. For more information, check out the below article led by Charles L. Steinhardt (Cosmic Dawn Center (DAWN) and University of Copenhagen) that describes the study.

Citation

“The BUFFALO HST Survey,” Charles L. Steinhardt et al 2020 ApJS 247 64. doi:10.3847/1538-4365/ab75ed

MCPM cosmic web reconstruction

The image above and its zoomed-in insets show a reconstruction of the cosmic web — a vast network of filamentary structures of matter spanning the universe. Simulations indicate that the universe’s matter should be organized into these complex threads, but this model has proven difficult to test observationally; most of the material is invisible dark matter, and the remainder is diffuse and distant, making it challenging to detect. A team of scientists led by Joseph Burchett (UC Santa Cruz) has now taken an unusual approach to modeling the cosmic web: they use the growth patterns of slime mold as a foundation. Slime mold has been shown to be very efficient when forming networks between sources of food — and when Burchett and collaborators model slime-mold-like networks forming between a sample of nearly 38,000 galaxies (the “food”) observed with the Sloan Digital Sky Survey, the model produces a web of filaments that well matches simulations of the cosmic web. The team further tests their model against Hubble observations of intergalactic medium (IGM) density, finding that the bulk of the IGM is, indeed, concentrated along cosmic web filaments traced by the slime mold model. To read more about this unusual study, check out the article below.

Citation

“Revealing the Dark Threads of the Cosmic Web,” Joseph N. Burchett et al 2020 ApJL 891 L35. doi:10.3847/2041-8213/ab700c

massive first-star binary

This still from a computer simulation (click for the full view!) shows the formation of a very early star system in the universe. In the gas-density volume rendering above, a binary composed of a single protostar (left) and a mini-triple set of protostars (right) has recently formed from the collapse and fragmentation of a primordial cloud of gas. The simulation, conducted by Kazuyuki Sugimura (University of Maryland; Tohoku University, Japan) and collaborators, follows not only what happens in the initial collapse of the cloud, but also how the subsequent evolution over the next ~100,000 years is influenced by the hot, ionizing radiation of the multiple stars that are forming (visible in this image as yellow bubbles of ionized gas around the poles of the stellar systems). Sugimura and collaborators’ work suggests that the first stars in the universe commonly formed as massive binary or multiple systems. To learn more about the study, check out the article below.

Citation

“The Birth of a Massive First-star Binary,” Kazuyuki Sugimura et al 2020 ApJL 892 L14. doi:10.3847/2041-8213/ab7d37

SPT-CL J2106-5844

You’re looking at SPT-CL J2106-5844, the most massive distant (farther than roughly 8 billion light-years) galaxy cluster known. This composite image (click for the full view) shows the field of the cluster, which spans a distance of roughly 3 million light-years across, in three Hubble color filters. The overlaid contours show the distribution of mass within the cluster, as recently determined by a team of scientists led by Jinhyub Kim (Yonsei University, Republic of Korea; University of California, Davis). Kim and collaborators used weak gravitational lensing — slight distortions in the shapes of background galaxies caused when their light is bent by the massive gravitational pull of this cluster — to map out the tremendous mass of SPT-CL J2106-5844. They find this cluster weighs in at a whopping ~1 quadrillion (1015) solar masses! Studying this distant, monster cluster can help us place constraints on how the universe’s large-scale structure formed and evolved. To read more about what the authors learned, check out the article below.

Citation

“Precise Mass Determination of SPT-CL J2106-5844, the Most Massive Cluster at z > 1,” Jinhyub Kim et al 2019 ApJ 887 76. doi:10.3847/1538-4357/ab521e

DSHARP disks

Are baby planets responsible for the gaps and rings we’ve spotted in the disks that surround distant, young stars? A new study led by Christophe Pinte (Monash University, Australia; Univ. Grenoble Alpes, France) has found evidence supporting this theory in the images of eight circumstellar disks observed in the Disk Substructures at High Angular Resolution (DSHARP) project. DSHARP uses the Atacama Large Millimeter/submillimeter Array (ALMA) to explore the gas distributed within the disks around young stars. In the image above (click for the full view!) the left-most panel shows the 1.3-millimeter dust continuum images of five complex circumstellar disks. The panels to the right show gas measurements for each disk in different velocity channels, revealing “velocity kinks” — deviations from the normal Keplerian velocity expected from unperturbed, orbiting gas. According to Pinte and collaborators, the kinks signatures of planets that perturb the gas flow in their vicinity. For more information, check out the article below.

Citation

“Nine Localized Deviations from Keplerian Rotation in the DSHARP Circumstellar Disks: Kinematic Evidence for Protoplanets Carving the Gaps,” C. Pinte et al 2020 ApJL 890 L9. doi:10.3847/2041-8213/ab6dda

galaxy cluster SPT-CL J0512−3848

The gravitational warping of distant starlight seen here (click for the full view) is caused by a galaxy cluster located nearly 4 billion light-years away, visible at the center of this image. Clusters of galaxies are the largest gravitationally bound systems in the universe, and their abundance and distribution can reveal information about how the universe expanded and how its structure formed and evolved. A team using the South Pole Telescope recently conducted a new survey — the SPTpol Extended Cluster Survey — of 2,770 square degrees of sky, hunting for the signatures that galaxy clusters imprint on the cosmic microwave background spectrum. In a publication led by Lindsey Bleem (Argonne National Laboratory, University of Chicago), the team describes the result: the discovery of 266 cluster candidates, 244 of which have already been confirmed visually via archival and follow-up observations like the one shown above (taken with the PISCO imager on the 6.5 m Magellan/Clay telescope at Las Campanas Observatory in Chile). To learn more about the study, check out the original article below.

Citation

“The SPTpol Extended Cluster Survey,” L. E. Bleem et al 2020 ApJS 247 25. doi:10.3847/1538-4365/ab6993

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