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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

radio harp

Look closely at this radio image (click for the full view!) and you might see why scientists have named this phenomenon a radio “harp”. These remarkable near-parallel lines of emission — which are seemingly sorted by length, so that they resemble a harp with radio-emitting strings — span several light-years and can be spotted in the center regions of our galaxy. In a new study led by Timon Thomas (Leibniz-Institute for Astrophysics Potsdam), a team of scientists argues that this cosmic music is caused by a massive star or a pulsar (a magnetized neutron star) plunging through an ordered magnetic field in the galactic center. As the star crosses (moving upward, in the image above) bundles of field lines, it discharges high-energy cosmic rays that travel in either direction along the bundles, emitting radio waves. Thomas and collaborators use observations of these radio harps to study how cosmic rays propagate along magnetic fields. To learn more about what they found, check out the article below.

Citation

“Probing Cosmic-Ray Transport with Radio Synchrotron Harps in the Galactic Center,” Timon Thomas et al 2020 ApJL 890 L18. doi:10.3847/2041-8213/

Rosette Nebula

Rosette Nebula Gemini

Gemini infrared image of the center of the Rosette Nebula. The cyan-outlined region corresponds to the cyan-outlined region in the cover image above. [Mužić et al. 2019]

You’re looking at a 55’ x 55’ Deep Sky Survey image of the Rosette Nebula (click for the full view), a large, spherical, star-forming region located about 5,200 light-years away. In a recent study led by Koraljka Mužić (University of Lisbon, Portugal), a team of scientists has used the Gemini South telescope in Chile to obtain near-infrared images from deep in the heart of the nebula. Zooming in on a region of less than 25 square light-years (the central cyan-outlined region in the photos above and to the right), Mužić and collaborators have imaged the center of NGC 2244, a young, high-density stellar cluster forming massive stars. In their study, the authors seek to understand how low-mass stars and brown dwarfs form and evolve among their high-mass siblings in these extreme environments. To learn more, check out the article below.

Citation

“Looking Deep into the Rosette Nebula’s Heart: The (Sub)stellar Content of the Massive Young Cluster NGC 2244,” Koraljka Mužić et al 2019 ApJ 881 79. doi:10.3847/1538-4357/ab2da4

galactic dust to 500 pc

This complex map (click for a closer look) shows the locations of dust in our galaxy, as measured out to a distance of 500 pc (roughly 1,630 light-years). Dust reveals important information about galactic structure and star formation — but it can also present a hindrance, dimming and reddening faraway sources. To correctly interpret distant observations, we need an accurate picture of how dust is distributed within our galaxy. A team of scientists led by Gregory Green (Stanford University; Max Planck Institute for Astronomy, Germany) have now built a detailed three-dimensional map of dust reddening in our galaxy out to a distance of a few kiloparsecs (~10,000 light-years). The authors accomplished this by using Gaia parallaxes and stellar photometry from Pan-STARRS 1 and 2MASS to infer the distances, reddenings, and types of 799 million stars. Their 3D map and data are freely accessible for use; for more information, see the article linked below.

Bonus

Check out the authors’ video, which reveals the 3D-ness of the dust distribution as the virtual camera orbits on a 25-pc loop around the Sun.

Citation

“A 3D Dust Map Based on Gaia, Pan-STARRS 1, and 2MASS,” Gregory M. Green et al 2019 ApJ 887 93. doi:10.3847/1538-4357/ab5362

NGC 1068

Editor’s note: AAS Nova will be on vacation for the remainder of this week. Our regular posting schedule will resume on Jan 21.

NGC 1068 SOFIA/HST

The magnetic field lines from SOFIA/HAWC+’s observations are here shown overplotted on this Hubble image of NGC 1068. [Lopez-Rodriguez et al. 2019]

This cryptic image is the (false-color) view of a large spiral galaxy, NGC 1068, at the far-infrared wavelength of 89 μm (click for the full view). The tiny hairs threading the galaxy show the magnetic field lines — ordinarily invisible — that pervade interstellar space. This magnetic field has been imaged using the HAWC+ instrument on SOFIA, a telescope that points out of a Boeing 747 airplane, observing above 99% of the Earth’s infrared-blocking atmosphere. HAWC+ has captured not only the infrared flux of the thermally emitting dust in NGC 1068, but also the polarization of the dust, which tells us what direction the magnetic field points at each location. By piecing this information together, a team led by Enrique Lopez-Rodriguez (SOFIA Science Center) has determined the overall structure of NGC 1068’s magnetic field, finding that it closely traces all the way along the spiral arms of the galaxy (24,000 light-years across!). To learn more about the authors’ results, check out the original article below.

Citation

“SOFIA/HAWC+ Traces the Magnetic Fields in NGC 1068,” Enrique Lopez-Rodriguez et al 2020 ApJ 888 66. doi:10.3847/1538-4357/ab5849

Hevelius's observatory

sunspot observations

Example page of Selenographia with a sunspot drawing made by Hevelius in September 1643. [Carrasco et al. 2019; Selenographia, courtesy of the Library of the Astronomical Obs. of the Spanish Navy]

Click on the image above to see the full view of the observatory of Johannes Hevelius, a Polish astronomer who lived in the 1600s. This print is found in Hevelius’s book Selenographia and is reproduced courtesy of the Library of the Astronomical Observatory of the Spanish Navy in a recent solar activity research study led by Victor Carrasco (University of Extremadura, Spain and Southwest Research Institute). Hevelius used his observatory to chart daily observations of sunspots (note, in the above image, the projection of the Sun’s disk from the telescope coming through the left wall onto a vertical screen at the right). His records from 1642 to 1645 are the only systematic sunspot observations we have from just before the Maunder Minimum, a prolonged period of reduced solar activity between 1645 and 1715. Carrasco and collaborators have now reevaluated Hevelius’s observations, using them to explore the first hints of this quiet time for the Sun. For more information, check out the original article below.

Citation

“Sunspot Characteristics at the Onset of the Maunder Minimum Based on the Observations of Hevelius,” V. M. S. Carrasco et al 2019 ApJ 886 18. doi:10.3847/1538-4357/ab4ade

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