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Dissecting stellar chemical abundance space with t-SNE
Guiglion, G.; Anders, F.; Chiappini, C. +4 more
In the era of large-scale Galactic astronomy and multi-object spectroscopic stellar surveys, the sample sizes and the number of available stellar chemical abundances have reached dimensions in which it has become difficult to process all the available information in an effective manner. In this paper we demonstrate the use of a dimensionality-redu…
The First Tidally Disrupted Ultra-faint Dwarf Galaxy?: A Spectroscopic Analysis of the Tucana III Stream
Bechtol, K.; Smith, M.; D'Andrea, C. B. +69 more
We present a spectroscopic study of the tidal tails and core of the Milky Way satellite Tucana III, collectively referred to as the Tucana III stream, using the 2dF+AAOmega spectrograph on the Anglo-Australian Telescope and the IMACS spectrograph on the Magellan Baade Telescope. In addition to recovering the brightest nine previously known member …
Spiral Arms in Disks: Planets or Gravitational Instability?
Dong, Ruobing; Najita, Joan R.; Brittain, Sean
Spiral arm structures seen in scattered-light observations of protoplanetary disks can potentially serve as signposts of planetary companions. They can also lend unique insights into disk masses, which are critical in setting the mass budget for planet formation but are difficult to determine directly. A surprisingly high fraction of disks that ha…
The XMM Cluster Outskirts Project (X-COP): Thermodynamic properties of the intracluster medium out to R200 in Abell 2319
Hurier, G.; Pointecouteau, E.; Molendi, S. +5 more
Aims: We present the joint analysis of the X-ray and Sunyaev-Zel'dovich (SZ) signals in Abell 2319, the galaxy cluster with the highest signal-to-noise ratio in SZ Planck maps and that has been surveyed within our XMM-Newton Cluster Outskirts Project (X-COP), a very large program which aims to grasp the physical condition in 12 local (z < …
Constraining a Thin Dark Matter Disk with G a i a
Safdi, Benjamin R.; Schutz, Katelin; Lin, Tongyan +1 more
If a component of the dark matter has dissipative interactions, it could collapse to form a thin dark disk in our Galaxy that is coplanar with the baryonic disk. It has been suggested that dark disks could explain a variety of observed phenomena, including periodic comet impacts. Using the first data release from the Gaia space observatory, we sea…
Empirical photometric calibration of the Gaia red clump: Colours, effective temperature, and absolute magnitude
Arenou, F.; Babusiaux, C.; Turon, C. +2 more
Context. Gaia Data Release 1 allows the recalibration of standard candles such as the red clump stars. To use those stars, they first need to be accurately characterised. In particular, colours are needed to derive interstellar extinction. As no filter is available for the first Gaia data release and to avoid the atmosphere model mismatch, an empi…
Frequently Occurring Reconnection Jets from Sunspot Light Bridges
Solanki, Sami K.; Ni, Lei; Chen, Yajie +12 more
Solid evidence of magnetic reconnection is rarely reported within sunspots, the darkest regions with the strongest magnetic fields and lowest temperatures in the solar atmosphere. Using the world’s largest solar telescope, the 1.6 m Goode Solar Telescope, we detect prevalent reconnection through frequently occurring fine-scale jets in the Hα line …
GALACTICNUCLEUS: A high angular resolution JHKs imaging survey of the Galactic centre. I. Methodology, performance, and near-infrared extinction towards the Galactic centre
Nishiyama, S.; Hilker, M.; de Zeeuw, P. T. +9 more
Context. The Galactic centre (GC) is of fundamental astrophysical interest, but existing near-infrared surveys fall short covering it adequately, either in terms of angular resolution, multi-wavelength coverage, or both. Here we introduce the GALACTICNUCLEUS survey, a JHKs imaging survey of the centre of the Milky Way with a 0.2″
A Close Relationship between Lyα and Mg II in Green Pea Galaxies
Verhamme, Anne; Scarlata, Claudia; Henry, Alaina +2 more
The Mg II λλ2796, 2803 doublet is often used to measure interstellar medium absorption in galaxies, thereby serving as a diagnostic for feedback and outflows. However, the interpretation of Mg II remains confusing, due to resonant trapping and re-emission of the photons, analogous to Lyα. Therefore, in this paper, we present new MMT Blue Channel S…
Kronos and Krios: Evidence for Accretion of a Massive, Rocky Planetary System in a Comoving Pair of Solar-type Stars
Hogg, David W.; Price-Whelan, Adrian M.; Spergel, David N. +3 more
We report and discuss the discovery of a significant difference in the chemical abundances of a comoving pair of bright solar-type stars, HD 240430 and HD 240429. The two stars have an estimated 3D separation of ≈0.6 pc (≈0.01 pc projected) at a distance of r ≈ 100 pc with nearly identical 3D velocities, as inferred from Gaia TGAS parallaxes and p…