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The Geometry of Cold, Metal-enriched Gas around Galaxies at z ∼ 1.2
van Dokkum, Pieter; York, Donald G.; Chisholm, John +10 more
We present the first results from a Hubble Space Telescope Wide Field Camera 3/Infrared program, which obtained direct imaging and grism observations of galaxies near quasar sightlines with a high frequency of uncorrelated foreground Mg II absorption. These highly efficient observations targeted 54 Mg II absorbers along the line of sight to nine q…
Evidence for Radial Expansion at the Core of the Orion Complex with Gaia EDR3
Meingast, Stefan; Alves, João; Zucker, Catherine +6 more
We present a phase-space study of two stellar groups located at the core of the Orion Complex: Briceño-1 and Orion Belt Population-near (OBP-near). We identify the groups with the unsupervised clustering algorithm, Shared Nearest Neighbor (SNN), which previously identified 12 new stellar substructures in the Orion Complex. For each of the two grou…
The Swift bulge survey: motivation, strategy, and first X-ray results
Maccarone, T. J.; Degenaar, N.; Wijnands, R. +12 more
Very faint X-ray transients (VFXTs) are X-ray transients with peak X-ray luminosities (LX) of L$_X \lesssim 10^{36}$ erg s-1, which are not well understood. We carried out a survey of 16 deg2 of the Galactic Bulge with the Swift Observatory, using short (60 s) exposures, and returning every 2 weeks for 19 epochs in…
Molecular mapping of the PDS70 system. No molecular absorption signatures from the forming planet PDS70 b
Quanz, S. P.; Snellen, I. A. G.; Stolker, T. +7 more
Context. Determining the chemical properties of the atmosphere of young forming gas giants might shed light on the location their formation occurred and the mechanisms involved.
Aims: Our aim was to detect molecules in the atmosphere of the young forming companion PDS70 b by searching for atmospheric absorption features typical of substellar …
Did Sgr cause the vertical waves in the solar neighbourhood?
Bovy, Jo; Bennett, Morgan
The vertical distribution of stars in the solar neighbourhood is not in equilibrium but contains a wave signature in both density and velocity space originating from a perturbation. With the discovery of the phase-space spiral in Gaia data release (DR) 2, determining the origin of this perturbation has become even more urgent. We develop and test …
The orbit and stellar masses of the archetype colliding-wind binary WR 140
Corcoran, Michael F.; Couperus, Andrew; Moffat, Anthony F. J. +33 more
We present updated orbital elements for the Wolf-Rayet (WR) binary WR 140 (HD 193793; WC7pd + O5.5fc). The new orbital elements were derived using previously published measurements along with 160 new radial velocity measurements across the 2016 periastron passage of WR 140. Additionally, four new measurements of the orbital astrometry were collect…
Velocity Dispersion of the GD-1 Stellar Stream
Naidu, Rohan P.; Bonaca, Ana; Gialluca, Megan T.
Tidally dissolved globular clusters form thin stellar streams that preserve a historical record of their past evolution. We report a radial velocity dispersion of 2.1 ± 0.3 km s-1 in the GD-1 stellar stream using a sample of 43 spectroscopically confirmed members. The GD-1 velocity dispersion is constant over the surveyed ≈15° span of t…
3D spectroscopic analysis of helium-line white dwarfs
Ludwig, Hans-Günter; Bergeron, Pierre; Tremblay, Pier-Emmanuel +3 more
In this paper, we present corrections to the spectroscopic parameters of DB and DBA white dwarfs with -10.0 ≤ log (H/He) ≤ -2.0, 7.5 ≤ log g ≤ 9.0, and $12\, 000$ ≲ Teff $\lesssim 34\, 000\,\mathrm{ K}$ , based on 282 3D atmospheric models calculated with the CO5BOLD radiation-hydrodynamics code. These corrections arise due t…
The Most Metal-poor Stars in the Magellanic Clouds Are r-process Enhanced
Casey, Andrew R.; Simon, Joshua D.; Ji, Alexander P. +2 more
The chemical abundances of a galaxy's metal-poor stellar population can be used to investigate the earliest stages of its formation and chemical evolution. The Magellanic Clouds are the most massive of the Milky Way's satellite galaxies and are thought to have evolved in isolation until their recent accretion by the Milky Way. Unlike the Milky Way…
Galactic bar resonances inferred from kinematically hot stars in Gaia EDR3
Cropper, Mark; Ciucă, Ioana; Seabroke, George +5 more
Using a numerical simulation of an isolated barred disc galaxy, we first demonstrate that the resonances of the inner bar structure induce more prominent features in the action space distribution for the kinematically hotter stars, which are less sensitive to the local perturbation, such as the transient spiral arms. Then, we analyse the action di…