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VLT/FLAMES high-resolution chemical abundances in Sculptor: a textbook dwarf spheroidal galaxy
Spite, M.; Skúladóttir, Á.; Jablonka, P. +12 more
We present detailed chemical abundances for 99 red-giant branch stars in the centre of the Sculptor dwarf spheroidal galaxy, which have been obtained from high-resolution VLT/FLAMES spectroscopy. The abundances of Li, Na, α-elements (O, Mg, Si, Ca Ti), iron-peak elements (Sc, Cr, Fe, Co, Ni, Zn), and r- and s-process elements (Ba, La, Nd, Eu) were…
First Gaia Dynamics of the Andromeda System: DR2 Proper Motions, Orbits, and Rotation of M31 and M33
van der Marel, Roeland P.; Watkins, Laura L.; Fardal, Mark A. +5 more
The 3D velocities of M31 and M33 are important for understanding the evolution and cosmological context of the Local Group. Their most massive stars are detected by Gaia, and we use Data Release 2 (DR2) to determine the galaxy proper motions (PMs). We select galaxy members based on, e.g., parallax, PM, color-magnitude diagram location, and local s…
SDSS-IV MaStar: A Large and Comprehensive Empirical Stellar Spectral Library—First Release
Zhao, Gang; Bizyaev, Dmitry; Kinemuchi, Karen +45 more
We present the first release of the MaNGA Stellar Library (MaStar), which is a large, well-calibrated, high-quality empirical library covering the wavelength range 3622-10354 Å at a resolving power of R ∼ 1800. The spectra were obtained using the same instrument as used by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) project, by…
Cosmological Constraints from Multiple Probes in the Dark Energy Survey
Bacon, D.; Bechtol, K.; Challis, P. +161 more
The combination of multiple observational probes has long been advocated as a powerful technique to constrain cosmological parameters, in particular dark energy. The Dark Energy Survey has measured 207 spectroscopically confirmed type Ia supernova light curves, the baryon acoustic oscillation feature, weak gravitational lensing, and galaxy cluster…
SILVERRUSH. VIII. Spectroscopic Identifications of Early Large-scale Structures with Protoclusters over 200 Mpc at z ∼ 6-7: Strong Associations of Dusty Star-forming Galaxies
Ono, Yoshiaki; Ouchi, Masami; Goto, Tomotsugu +32 more
We have obtained three-dimensional maps of the universe in ∼200 × 200 × 80 comoving Mpc3 (cMpc3) volumes each at z = 5.7 and 6.6 based on a spectroscopic sample of 179 galaxies that achieves ≳80% completeness down to the Lyα luminosity of {log}({L}Lyα }/[{erg} {{{s}}}-1])=43.0, based on our Keck and Gemi…
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 …