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Temperatures and Metallicities of M Dwarfs in the APOGEE Survey
Hogg, David W.; Mann, Andrew W.; Burgasser, Adam +1 more
M dwarfs have enormous potential for our understanding of structure and formation on both Galactic and exoplanetary scales through their properties and compositions. However, current atmosphere models have limited ability to reproduce spectral features in stars at the coolest temperatures (Teff < 4200 K) and to fully exploit the info…
The First Ultracompact Roche Lobe-Filling Hot Subdwarf Binary
Duev, Dmitry A.; Riddle, Reed; Szkody, Paula +29 more
We report the discovery of the first short-period binary in which a hot subdwarf star (sdOB) filled its Roche lobe and started mass transfer to its companion. The object was discovered as part of a dedicated high-cadence survey of the Galactic plane named the Zwicky Transient Facility and exhibits a period of P = 39.3401(1) minutes, making it the …
Birds of a Feather? Magellan/IMACS Spectroscopy of the Ultra-faint Satellites Grus II, Tucana IV, and Tucana V
Bechtol, K.; Smith, M.; Lidman, C. +55 more
We present Magellan/IMACS spectroscopy of three recently discovered ultra-faint Milky Way satellites, Grus II, Tucana IV, and Tucana V. We measure systemic velocities of Vhel = 110.0 ± 0.5 km s-1, Vhel = 15.9-1.7+1.8 km s-1, and Vhel=-36.2-2.2+2.5 km…
Constraining the Milky Way Mass Profile with Phase-space Distribution of Satellite Galaxies
Li, Ting S.; Wang, Wenting; Han, Jiaxin +3 more
We estimate the Milky Way (MW) halo properties using satellite kinematic data including the latest measurements from Gaia DR2. With a simulation-based 6D phase-space distribution function (DF) of satellite kinematics, we can infer halo properties efficiently and without bias, and handle the selection function and measurement errors rigorously in t…
TESS Spots a Hot Jupiter with an Inner Transiting Neptune
Torres, Guillermo; Vanderburg, Andrew; Latham, David W. +48 more
Hot Jupiters are rarely accompanied by other planets within a factor of a few in orbital distance. Previously, only two such systems have been found. Here, we report the discovery of a third system using data from the Transiting Exoplanet Survey Satellite (TESS). The host star, TOI-1130, is an eleventh magnitude K-dwarf in Gaia G-band. It has two …
Spectral Signatures of Chromospheric Condensation in a Major Solar Flare
Allred, Joel; Graham, David R.; Zangrilli, Luca +3 more
We study the evolution of chromospheric line and continuum emission during the impulsive phase of the X-class SOL2014-09-10T17:45 solar flare. We extend previous analyses of this flare to multiple chromospheric lines of Fe I, Fe II, Mg II, C I, and Si II observed with the Interface Region Imaging Spectrograph, combined with radiative-hydrodynamica…
The Regulation of Galaxy Growth along the Size-Mass Relation by Star Formation, as Traced by Hα in KMOS3D Galaxies at 0.7 ≲ z ≲ 2.7
Übler, Hannah; van Dokkum, Pieter; Momcheva, Ivelina +24 more
We present half-light sizes measured from Hα emission tracing star formation in 281 star-forming galaxies from the KMOS3D survey at 0.7≲ z ≲ 2.7. Sizes are derived by fitting 2D exponential disk models, with bootstrap errors averaging 20%. Hα sizes are a median (mean) of 1.19 (1.26) times larger than those of the stellar continuum—which…
Three-component Kinematics of Multiple Stellar Populations in Globular Clusters with Gaia and VLT
Milone, A. P.; Cordoni, G.; Marino, A. F. +5 more
The internal dynamics of multiple stellar populations in globular clusters (GCs) provides unique constraints on the physical processes responsible for their formation. Specifically, the present-day kinematics of cluster stars, such as rotation and velocity dispersion, could be related to the initial configuration of the system. In recent work, we …
Two Directly Imaged, Wide-orbit Giant Planets around the Young, Solar Analog TYC 8998-760-1
Ginski, Christian; Kenworthy, Matthew A.; Mamajek, Eric E. +9 more
Even though tens of directly imaged companions have been discovered in the past decades, the number of directly confirmed multiplanet systems is still small. Dynamical analysis of these systems imposes important constraints on formation mechanisms of these wide-orbit companions. As part of the Young Suns Exoplanet Survey we report the detection of…
New Conductive Opacities for White Dwarf Envelopes
Blouin, Simon; Saumon, Didier; Shaffer, Nathaniel R. +1 more
Thanks to their continuous cooling and relative simplicity, white dwarf stars are routinely used to measure the ages of stellar populations. The usefulness of white dwarfs as cosmochronometers depends on the availability of accurate cooling models. A key ingredient of those models is conductive opacities, which largely govern the cooling rate. In …