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The Pre-He White Dwarf in the Post-mass Transfer Binary EL CVn
Gies, Douglas R.; Lester, Kathryn V.; Wang, Luqian +8 more
EL CVn is the prototype of a class of eclipsing binaries that consist of an A- or F-type main-sequence star and a hot, low-mass, pre-He white dwarf (pre-He WD), the stripped down remains of the former mass donor. Here we present the first direct detection and characterization of the spectrum of the pre-He WD in EL CVn that was made possible throug…
Scaling K2. III. Comparable Planet Occurrence in the FGK Samples of Campaign 5 and Kepler
Schlieder, Joshua E.; Petigura, Erik A.; Crossfield, Ian J. M. +5 more
Using our K2 Campaign 5 fully automated planet-detection data set (43 planets), which has corresponding measures of completeness and reliability, we infer an underlying planet population model for the FGK dwarf sample (9257 stars). Implementing a broken power law for both the period and radius distributions, we find an overall planet occurrence of…
Candidate Brown-dwarf Microlensing Events with Very Short Timescales and Small Angular Einstein Radii
Han, Cheongho; Udalski, Andrzej; Lee, Chung-Uk +65 more
Short-timescale microlensing events are likely to be produced by substellar brown dwarfs (BDs), but it is difficult to securely identify BD lenses based on only event timescales ${t}_{{\rm{E}}} because short-timescale events can also be produced by stellar lenses with high relative lens-source proper motions. In this paper, we report three strong …
Hubble Space Telescope Astrometry in the Orion Nebula Cluster: Census of Low-mass Runaways
Gennaro, Mario; Bellini, Andrea; Strampelli, Giovanni +6 more
We present a catalog of high-precision proper motions in the Orion Nebula Cluster (ONC), based on Treasury Program observations with the Hubble Space Telescope's (HST) ACS/WFC camera. Our catalog contains 2454 objects in the magnitude range of 14.2 < mF775W < 24.7, thus probing the stellar masses of the ONC from ∼0.4 M⊙…
Astraea: Predicting Long Rotation Periods with 27 Day Light Curves
Angus, Ruth; Grunblatt, Sam; Agüeros, Marcel A. +5 more
The rotation periods of planet-hosting stars can be used for modeling and mitigating the impact of magnetic activity in radial velocity measurements and can help constrain the high-energy flux environment and space weather of planetary systems. Millions of stars and thousands of planet hosts are observed with the Transiting Exoplanet Survey Satell…
Cloud Atlas: High-precision HST/WFC3/IR Time-resolved Observations of Directly Imaged Exoplanet HD 106906b
Schneider, Glenn; Metchev, Stanimir; Apai, Dániel +10 more
HD 106906b is an $\sim 11{M}_{\mathrm{Jup}}, ∼15 Myr old directly imaged exoplanet orbiting at an extremely large distance from its host star. The wide separation (7"11) between HD 106906b and its host star greatly reduces the difficulty in direct-imaging observations, making it one of the most favorable directly imaged exoplanets for detailed cha…
The Pre-He White Dwarfs in Eclipsing Binaries. I. WASP 0131+28
Koo, Jae-Rim; Hong, Kyeongsoo; Lee, Jae Woo +1 more
We report the first BV light curves and high-resolution spectra of the post-mass transfer binary star WASP 0131+28 to study the absolute properties of extremely low-mass white dwarfs. From the observed spectra, the double-lined radial velocities were derived, and the effective temperature and rotational velocity of the brighter, more massive prima…
Galaxy and Mass Assembly: A Comparison between Galaxy-Galaxy Lens Searches in KiDS/GAMA
Holwerda, Benne W.; Hopkins, Andrew M.; Bilicki, Maciej +9 more
Strong gravitational lenses are a rare and instructive type of astronomical object. Identification has long relied on serendipity, but different strategies—such as mixed spectroscopy of multiple galaxies along the line of sight, machine-learning algorithms, and citizen science—have been employed to identify these objects as new imaging surveys bec…
Bayesian Characterization of Main-sequence Binaries in the Old Open Cluster NGC 188
Cohen, Roger E.; von Hippel, Ted; Geller, Aaron M.
The binary fractions of open and globular clusters yield powerful constraints on their dynamical state and evolutionary history. We apply publicly available Bayesian analysis tools to a UBV RIJHK S photometric catalog of the open cluster NGC 188 to detect and characterize photometric binaries along the cluster main sequence. This tech…
Statistics of Wide Pre-main-sequence Binaries in the Orion OB1 Association
Tokovinin, Andrei; Petr-Gotzens, Monika G.; Briceño, Cesar
Statistics of low-mass pre-main-sequence binaries in the Orion OB1 association with separations ranging from 0"6 to 20″ (220 to 7400 au at 370 pc) are studied using images from the VISTA Orion mini survey and astrometry from Gaia. The input sample based on the CVSO catalog contains 1137 stars of K and M spectral types (masses between 0.3 and 0.9 $…