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Resolved Young Binary Systems and Their Disks
Jensen, Eric L. N.; Carpenter, John; Ricci, Luca +4 more
We have conducted a survey of young single and multiple systems in the Taurus-Auriga star-forming region with the Atacama Large Millimeter Array (ALMA), substantially improving both the spatial resolution and sensitivity with which individual protoplanetary disks in these systems have been observed. These ALMA observations can resolve binary separ…
No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations
Montmessin, Franck; Belyaev, Denis A.; Fedorova, Anna A. +123 more
The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today1. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations2-5. These measur…
On the ridges, undulations, and streams in Gaia DR2: linking the topography of phase space to the orbital structure of an N-body bar
White, S. D. M.; Katz, D.; Fragkoudi, F. +7 more
We explore the origin of phase-space substructures revealed by the second Gaia data release in the disc of the Milky Way, such as the ridges in the Vϕ-r plane, the undulations in the Vϕ-r-Vr space and the streams in the Vϕ-Vr plane. We use a collisionless N-body simulation with cospatial thin …
A New Class of Changing-look LINERs
Cenko, S. Bradley; Duev, Dmitry A.; Rusholme, Ben +28 more
We report the discovery of six active galactic nuclei (AGNs) caught “turning on” during the first nine months of the Zwicky Transient Facility (ZTF) survey. The host galaxies were classified as low-ionization nuclear emission-line region galaxies (LINERs) by weak narrow forbidden line emission in their archival SDSS spectra, and detected by ZTF as…
Tracing the formation of the Milky Way through ultra metal-poor stars
Fouesneau, Morgan; Sestito, Federico; Navarro, Julio F. +11 more
We use Gaia DR2 astrometric and photometric data, published radial velocities and MESA models to infer distances, orbits, surface gravities, and effective temperatures for all ultra metal-poor stars ([Fe/H] < -4.0 dex) available in the literature. Assuming that these stars are old (> 11 Gyr) and that they are expected to belong to the Milky …
Intracluster light: a luminous tracer for dark matter in clusters of galaxies
Trujillo, Ignacio; Montes, Mireia
The bulk of stars in galaxy clusters are confined within their constituent galaxies. Those stars do not trace the extended distribution of dark matter well as they are located in the central regions of the cluster's dark matter subhaloes. A small fraction of stars is expected, however, to follow the global dark matter shape of the cluster. These a…
The Broad Absorption Line Tidal Disruption Event iPTF15af: Optical and Ultraviolet Evolution
Cenko, S. B.; Veilleux, S.; Bloom, J. S. +16 more
We present multiwavelength observations of the tidal disruption event (TDE) iPTF15af, discovered by the intermediate Palomar Transient Factory survey at redshift z = 0.07897. The optical and ultraviolet (UV) light curves of the transient show a slow decay over 5 months, in agreement with previous optically discovered TDEs. It also has a comparable…
A Second Terrestrial Planet Orbiting the Nearby M Dwarf LHS 1140
Latham, David W.; Esquerdo, Gilbert A.; Tan, Thiam-Guan +27 more
LHS 1140 is a nearby mid-M dwarf known to host a temperate rocky super-Earth (LHS 1140 b) on a 24.737-day orbit. Based on photometric observations by MEarth and Spitzer as well as Doppler spectroscopy from the High Accuracy Radial velocity Planet Searcher, we report the discovery of an additional transiting rocky companion (LHS 1140 c) with a mass…
Luminous red novae: Stellar mergers or giant eruptions?
Drake, A. J.; Sollerman, J.; Djorgovski, S. G. +36 more
We present extensive datasets for a class of intermediate-luminosity optical transients known as luminous red novae. They show double-peaked light curves, with an initial rapid luminosity rise to a blue peak (at -13 to -15 mag), which is followed by a longer-duration red peak that sometimes is attenuated, resembling a plateau. The progenitors of t…
New View of the Solar Chromosphere
De Pontieu, Bart; Carlsson, Mats; Hansteen, Viggo H.
The solar chromosphere forms a crucial, yet complex and until recently poorly understood, interface between the solar photosphere and the heliosphere. Advances in high-resolution instrumentation, adaptive optics, image reconstruction techniques, and space-based observatories allow unprecedented high-resolution views of the finely structured and hi…