Search Publications
Stellar Parameters for Pulsating B-star Candidates in the Kepler Field
McSwain, M. Virginia; Hanes, Richard J.; Waskie, Steven +3 more
The field of asteroseismology has enjoyed a large swath of data coming from recent missions (e.g., CoRoT, Kepler, K2). This wealth of new data has allowed the field to expand beyond the previous limitation of a few extremely bright and evolved stars. Asteroseismology relies on accurate surface measurements for boundary conditions, but the predicte…
Two Long-period Cataclysmic Variable Stars: ASASSN-14ho and V1062 Cyg
Thorstensen, John R.; Paterson, Kerry; Hviding, Raphael E. +5 more
We report spectroscopy and photometry of the cataclysmic variable stars ASASSN-14ho and V1062 Cyg. Both are dwarf novae with spectra dominated by their secondary stars, which we classify approximately as K4 and M0.5, respectively. Their orbital periods, determined mostly from the secondary stars’ radial velocities, proved to be nearly identical, r…
Comparison of the PPMXL and UCAC5 Catalogs with the Gaia DR2
Liu, N.; Zhu, Z.; Liu, J. -C. +3 more
Astrometric ground-based catalogs usually suffer from varied systematic errors. These systematic errors were hard to detect because there was no independent reference catalog complete to very faint limiting magnitudes (∼20 mag). This situation has changed since the second data release of the Gaia mission (Gaia DR2). We aim to investigate positions…
A Fast Approximate Approach to Microlensing Survey Analysis
Pepper, Joshua; Khakpash, Somayeh; Penny, Matthew
Microlensing can be used to discover exoplanets of a wide range of masses with orbits beyond ∼1 au, and even free-floating planets. The Wide Field Infrared Survey Telescope (WFIRST) mission will use microlensing to discover approximately 1600 planets by monitoring ∼100 million stars to find ∼50,000 microlensing events. Modeling each microlensing e…
Spectroscopic Redshift of the Gamma-Ray Blazar B2 1215+30 from Lyα Emission
Furniss, A.; Johnson, C. A.; Williams, D. A. +4 more
We report on Cosmic Origin Spectrograph observations of the gamma-ray bright blazar B2 1215+30, collected in 2015 November. These observations allow for the confirmation of the source redshift from the detection of a Lyα emission feature at λ ∼ 1374 Å. The emission feature places the source at a redshift of z = 0.1305 ± 0.003, confirming the sourc…
He II Emission from Wolf-Rayet Stars as a Tool for Measuring Dust Reddening
Leitherer, Claus; Faisst, Andreas; Lee, Janice C.
We calibrated a technique to measure dust attenuation in star-forming galaxies. The technique utilizes the stellar-wind lines in Wolf-Rayet stars, which are widely observed in galaxy spectra. The He II 1640 and 4686 features are recombination lines whose ratio is largely determined by atomic physics. Therefore they can serve as a stellar dust prob…
Stellar Occultation by Comet 67P/Churyumov-Gerasimenko Observed with Rosetta's Alice Far-ultraviolet Spectrograph
Parker, Joel Wm.; Bertaux, Jean-Loup; Stern, S. Alan +13 more
Following our previous detection of ubiquitous {{{H}}}2{{O}} and {{{O}}}2 absorption against the far-ultraviolet continuum of stars located near the nucleus of Comet 67P/Churyumov-Gerasimenko, we present a serendipitously observed stellar occultation that occurred on 2015 September 13, approximately one month after the comet’…
Detection of a Low-mass Stellar Companion to the Accelerating A2IV Star HR 1645
Duchêne, Gaspard; Esposito, Thomas M.; Hom, Justin +51 more
The ∼500 Myr A2IV star HR 1645 has one of the most significant low-amplitude accelerations of nearby early-type stars measured from a comparison of the Hipparcos and Gaia astrometric catalogs. This signal is consistent with either a stellar companion with a moderate mass ratio (q ∼ 0.5) on a short period (P < 1 yr), or a substellar companion at…
Characterization of Low-mass K2 Planet Hosts Using Near-infrared Spectroscopy
Vanderburg, Andrew; Montet, Benjamin T.; Christiansen, Jessie L. +3 more
We present moderate resolution near-infrared spectra in the H, J, and K band of M-dwarf hosts to candidate transiting exoplanets discovered by NASA’s K2 mission. We employ known empirical relationships between spectral features and physical stellar properties to measure the effective temperature, radius, metallicity, and luminosity of our sample. …
DS Andromedae: A Detached Eclipsing Double-lined Spectroscopic Binary in the Galactic Cluster NGC 752
Frandsen, S.; Milone, E. F.; Schiller, S. J. +1 more
The Wilson-Devinney program has been used to analyze well-calibrated photometric and new radial velocity data to determine the properties and distance of DS Andromedae, a 1.01 day period, double-lined, totally eclipsing binary system of early-F spectral type and a likely member of the intermediate-age open cluster NGC 752. The determinations of ma…