Search Publications
Microphysics of KCl and ZnS Clouds on GJ 1214 b
Benneke, Björn; Gao, Peter
Clouds in the atmospheres of exoplanets confound characterization efforts by reducing, eliminating, and distorting the spectral signatures of molecular abundances. As such, interpretations of exoplanet spectra strongly depend on the choice of cloud model, many of which are highly simplified and lack predictive power. In this work, we use a cloud m…
Spatially Resolved Stellar Kinematics from LEGA-C: Increased Rotational Support in z ∼ 0.8 Quiescent Galaxies
Bell, Eric F.; Maseda, Michael V.; Franx, Marijn +18 more
We present stellar rotation curves and velocity dispersion profiles for 104 quiescent galaxies at z = 0.6-1 from the Large Early Galaxy Astrophysics Census (LEGA-C) spectroscopic survey. Rotation is typically probed across 10-20 kpc, or to an average of 2.7Re. Combined with central stellar velocity dispersions (σ0) this provi…
Resolving Quiescent Galaxies at z ≳ 2. II. Direct Measures of Rotational Support
Ellis, Richard S.; Belli, Sirio; Newman, Andrew B. +1 more
Stellar kinematics provide insights into the masses and formation histories of galaxies. At high redshifts, spatially resolving the stellar kinematics of quiescent galaxies is challenging due to their compact sizes. Using deep near-infrared spectroscopy, we have measured the resolved stellar kinematics of four quiescent galaxies at z = 1.95-2.64, …
Far-ultraviolet Activity Levels of F, G, K, and M Dwarf Exoplanet Host Stars
Loyd, R. O. Parke; Redfield, Seth; France, Kevin +4 more
We present a survey of far-ultraviolet (FUV; 1150-1450 Å) emission line spectra from 71 planet-hosting and 33 non-planet-hosting F, G, K, and M dwarfs with the goals of characterizing their range of FUV activity levels, calibrating the FUV activity level to the 90-360 Å extreme-ultraviolet (EUV) stellar flux, and investigating the potential for FU…
A Gap in the Lower Main Sequence Revealed by Gaia Data Release 2
Gies, Douglas R.; Henry, Todd J.; Jao, Wei-Chun +1 more
We present the discovery of a gap near M G ≈ 10 in the main sequence on the Hertzsprung-Russell Diagram (HRD) based on measurements presented in Gaia Data Release 2 (DR2). Using an observational form of the HRD with M G representing luminosity and G BP - G RP representing temperature, the gap present…
Calibrating the metallicity of M dwarfs in wide physical binaries with F-, G-, and K-primaries - I: High-resolution spectroscopy with HERMES: stellar parameters, abundances, and kinematics
Alonso-Floriano, F. J.; Caballero, J. A.; Montes, D. +7 more
We investigated almost 500 stars distributed among 193 binary or multiple systems made of late-F, G-, or early-K-primaries and late-K- or M-dwarf companion candidates. For all of them, we compiled or measured coordinates, J-band magnitudes, spectral types, distances, and proper motions. With these data, we established a sample of 192 physically bo…
Spectroscopic and physical parameters of Galactic O-type stars. III. Mass discrepancy and rotational mixing
Puls, J.; Langer, N.; Markova, N.
Context. Massive stars play a key role in the evolution of galaxies and our Universe.
Aims: Our goal is to compare observed and predicted properties of single Galactic O stars to identify and constrain uncertain physical parameters and processes in stellar evolution and atmosphere models.
Methods: We used a sample of 53 objects of all lu…
Old-Aged Primary Distance Indicators
Salaris, Maurizio; Matsunaga, Noriyuki; Beaton, Rachael L. +8 more
Old-aged stellar distance indicators are present in all Galactic structures (halo, bulge, disk) and in galaxies of all Hubble types and, thus, are immensely powerful tools for understanding our Universe. Here we present a comprehensive review for three primary standard candles from Population II: (i) RR Lyrae type variables (RRL), (ii) type II Cep…
Fast Estimation of Orbital Parameters in Milky Way-like Potentials
Bovy, Jo; Mackereth, J. Ted
Orbital parameters, such as eccentricity and maximum vertical excursion, of stars in the Milky Way are an important tool for understanding its dynamics and evolution, but calculation of such parameters usually relies on computationally expensive numerical orbit integration. We present and test a fast method for estimating these parameters using an…
Revised Gaia Data Release 2 passbands
Weiler, Michael
Context. The European Space Agency mission Gaia has published, with its second data release (DR2), a catalogue of photometric measurements for more than 1.3 billion astronomical objects in three passbands. The precision of the measurements in these passbands, denoted G, GBP, and GRP, reach down to the milli-magnitude level. T…