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Eri II

This beautiful 13’ x 13’ image (click for the full view!) holds more than meets the eye. Look closely at the small concentration of blue stars just to the left of center. This is Eridanus II, one of nine new ultra-faint galaxies discovered just last year around the Milky Way. Detected as part of the Dark Energy Survey (DES) and presented in a study led by Sergey E. Koposov (Institute of Astronomy, Cambridge), these new galaxies add to a growing list of very dim satellites that orbit within the Milky Way’s potential. Since their discovery, these DES satellites have been used to answer a number of astronomical questions. In particular, the large dark-matter fraction of these ultra-faint galaxies makes them excellent laboratories for testing models of dark matter in the universe. Check back with us on Wednesday to learn more about what Eridanus II has revealed about dark matter! And for more information on the nine DES-discovered ultra-faint satellites, check out the paper below.


Sergey E. Koposov et al 2015 ApJ 805 130. doi:10.1088/0004-637X/805/2/130

LMC supernova remnants

These vibrant images (click for the full view!) of supernova remnants in the Large Magellanic Cloud (LMC) were created by mapping data from the Chandra X-ray Telescope into three colors: red for 300–720 eV, green for 720–1100 eV, and blue for 1100–7000 eV. Three scientists at University of Texas at Arlington — Andrew Schenck, Sangwook Park, and Seth Post — created these maps in order to probe the composition of the LMC’s interstellar medium. The forward shocks of supernova remnants sweep up the interstellar medium as they expand, heating it and causing it to emit the X-rays that Chandra observes. Schenck, Park and Post used Chandra’s observations of these remnants to make new measurements of the interstellar metallicities in the LMC. To find out more, check out the paper below!


Andrew Schenck et al 2016 AJ 151 161. doi:10.3847/0004-6256/151/6/161

Jupiter global map

Zonal wind profile for Jupiter, describing the speed and direction of its winds at each latitude. [Simon et al. 2015]

Zonal wind profile for Jupiter, describing the speed and direction of its winds at each latitude. [Simon et al. 2015]

This global map of Jupiter’s surface (click for the full view!) was generated by the Hubble Outer Planet Atmospheres Legacy (OPAL) program, which aims to create new yearly global maps for each of the outer planets. Presented in a study led by Amy Simon (NASA Goddard Space Flight Center), the map above is the first generated for Jupiter in the first year of the OPAL campaign. It provides a detailed look at Jupiter’s atmospheric structure — including the Great Red Spot — and allowed the authors to measure the speed and direction of the wind across Jupiter’s latitudes, constructing an updated zonal wind profile for Jupiter.

In contrast to this study, the Juno mission (which will be captured into Jupiter’s orbit today after a 5-year journey to Jupiter!) will be focusing more on the features below Jupiter’s surface, studying its deep atmosphere and winds. Some of Juno’s primary goals are to learn about Jupiter’s composition, gravitational field, magnetic field, and polar magnetosphere. You can follow along with the NASATV livestream as Juno arrives at Jupiter tonight; orbit insertion coverage starts at 10:30 EDT.


Amy A. Simon et al 2015 ApJ 812 55. doi:10.1088/0004-637X/812/1/55

This beautiful mosaic of images of the Whirlpool galaxy (M51) and its companion was taken with the Advanced Camera for Surveys on the Hubble Space Telescope. This nearby, “grand-design spiral” galaxy has a rich population of star clusters, making it both a stunning target for imagery and an excellent resource for learning about stellar formation and evolution. In a recent study, Rupali Chandar (University of Toledo) and collaborators cataloged over 3,800 compact star clusters within this galaxy. They then used this catalog to determine the distributions for the clusters’ ages, masses, and sizes, which can provide important clues as to how star clusters form, evolve, and are eventually disrupted. You can read more about their study and what they discovered in the paper below.


Rupali Chandar et al 2016 ApJ 824 71. doi:10.3847/0004-637X/824/2/71


This image of a fireball was captured in the Czech Republic by cameras at a digital autonomous observatory in the village of Kunžak. This observatory is part of a network of stations known as the European Fireball Network, and this particular meteoroid detection, labeled EN130114, is notable because it has the lowest initial velocity of any natural object ever observed by the network. Led by David Clark (University of Western Ontario), the authors of a recent study speculate that before this meteoroid impacted Earth, it may have been a Temporarily Captured Orbiter (TCO). TCOs are near-Earth objects that make a few orbits of Earth before returning to heliocentric orbits. Only one has ever been observed to date, and though they are thought to make up 0.1% of all meteoroids, EN130114 is the first event ever detected that exhibits conclusive behavior of a TCO. For more information on EN130114 and why TCOs are important to study, check out the paper below!


David L. Clark et al 2016 AJ 151 135. doi:10.3847/0004-6256/151/6/135

This remarkable false-color, mid-infrared image (click for the full view!) was produced by the Wide-field Infrared Survey Explorer (WISE). It captures a tantalizing view of Sh 2-207 and Sh 2-208, the latter of which is one of the lowest-metallicity star-forming regions in the Galaxy. In a recent study led by Chikako Yasui (University of Tokyo and the Koyama Astronomical Observatory), a team of scientists has examined this region to better understand how star formation in low-metallicity environments differs from that in the solar neighborhood. The authors’ analysis suggests that sequential star formation is taking place in these low-metallicity regions, triggered by an expanding bubble (the large dashed oval indicated in the image) with a ~30 pc radius. You can find out more about their study by checking out the paper below!


Chikako Yasui et al 2016 AJ 151 115. doi:10.3847/0004-6256/151/5/115

RT turbulence

This image shows a computer simulation of the hydrodynamics within a supernova remnant. The mixing between the outer layers (where color represents the log of density) is caused by turbulence from the Rayleigh-Taylor instability, an effect that arises when the expanding core gas of the supernova is accelerated into denser shell gas. The past standard for supernova-evolution simulations was to perform them in one dimension and then, in post-processing, manually smooth out regions that undergo Rayleigh-Taylor turbulence (an intrinsically multidimensional effect). But in a recent study, Paul Duffell (University of California, Berkeley) has explored how a 1D model could be used to reproduce the multidimensional dynamics that occur in turbulence from this instability. For more information, check out the paper below!


Paul C. Duffell 2016 ApJ 821 76. doi:10.3847/0004-637X/821/2/76

TW Hya

This remarkable image (click for the full view!) is a high-resolution map of the 870 µm light emitted by the protoplanetary disk surrounding the young solar analog TW Hydrae. A recent study led by Sean Andrews (Harvard-Smithsonian Center for Astrophysics) presents these observations, obtained with the long-baseline configuration of the Atacama Large Millimeter/submillimeter Array (ALMA) at an unprecedented spatial resolution of ~1 AU. The data represent the distribution of millimeter-sized dust grains in this disk, revealing a beautiful concentric ring structure out to a radial distance of 60 AU from the host star. The apparent gaps in the disk could have any of three origins:

  1. Chemical: apparent gaps can be caused by condensation fronts of volatiles
  2. Magnetic: apparent gaps can be caused by radial magnetic pressure variations
  3. Dynamic: actual gaps can be caused by the clearing of dust by young planets.

For more information, check out the paper below!


Sean M. Andrews et al 2016 ApJ 820 L40. doi:10.3847/2041-8205/820/2/L40

Toothbrush Cluster

This stunning composite image shows the components of the galaxy cluster RX J0603.3+4214, located at a redshift of z=0.225. This image contains Chandra X-ray data (red), radio data from the Giant Metrewave Radio Telescope (green), and optical from the Subaru Telescope (background). The shape of the enormous (6.5 million light-years across!) radio relic, shown in green, gives this collection of galaxies its nickname: the “Toothbrush Cluster.”  A team of scientists led by Myungkook James Jee (Yonsei University and University of California, Davis) used Hubble and Subaru to study weak gravitational lensing by the Toothbrush Cluster, in order to determine how the cluster’s mass is distributed. Jee and collaborators found that most of the dark-matter mass is located in two large clumps on a north-south axis (shown by the white contours overlaid on the image), suggesting that the Toothbrush Cluster is the result of a past merger between two clusters. This violent merger is likely what caused the enormous “Toothbrush” radio relic. Check out the paper below for more information!


M. James Jee et al 2016 ApJ 817 179. doi:10.3847/0004-637X/817/2/179

common envelope simulation

This beautiful series of snapshots from a simulation (click for a better look!) shows what happens when two stars in a binary system become enclosed in the same stellar envelope. In this binary system, one of the stars has exhausted its hydrogen fuel and become a red giant, complete with an expanding stellar envelope composed of hydrogen and helium. Eventually, the envelope expands so much that the companion star falls into it, where it releases gravitational potential energy into the common envelope. A team led by Sebastian Ohlmann (Heidelberg Institute for Theoretical Studies and University of Würzburg) recently performed hydrodynamic simulations of this process. Ohlmann and collaborators discovered that the energy release eventually triggers large-scale flow instabilities, which leads to turbulence within the envelope. This process has important consequences for how these systems next evolve (for instance, determining whether or not a supernova occurs!). You can check out the authors’ video of their simulated stellar inspiral below, or see their paper for more images and results from their study.


Sebastian T. Ohlmann et al 2016 ApJ 816 L9. doi:10.3847/2041-8205/816/1/L9

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