Search Publications
Nearby Quintuple Systems κ Tucanae and ξ Scorpii
Tokovinin, Andrei
Architecture and parameters of two wide, nearby hierarchical systems containing five solar-type stars each, κ Tuc and ξ Sco, are studied. Using Gaia astrometry and photometry, masses are determined from visual orbits and isochrones, and effective temperatures from spectra or colors. Both systems are ∼2 Gyr old. Their spatial motion corresponds to …
Identifying Exo-Earth Candidates in Direct Imaging Data through Bayesian Classification
Apai, Dániel; Bixel, Alex
Future space telescopes may be able to directly image between approximately 10 and 100 planets with sizes and orbits consistent with habitable surface conditions (“exo-Earth candidates” or EECs), but observers will face difficulty in distinguishing these from the potentially hundreds of nonhabitable “false positives” which will also be detected. T…
The Statistics of Extended Debris Disks Measured with Gaia and Planck
Jain, Bhuvnesh; Nibauer, Jacob; Baxter, Eric
Thermal emission from debris disks around stars has been measured using targeted and resolved observations. We present an alternative likelihood-based approach in which temperature maps from the Planck cosmic microwave background (CMB) survey at 857 and 545 GHz are analyzed in conjunction with stellar positions from Gaia to estimate the fraction o…
Searching the Entirety of Kepler Data. I. 17 New Planet Candidates Including One Habitable Zone World
Kunimoto, Michelle; Ngo, Henry; Matthews, Jaymie M.
We present the results of an independent search of all ∼200,000 stars observed over the four year Kepler mission (Q1-Q17) for multiplanet systems, using a three-transit minimum detection criterion to search orbital periods up to hundreds of days. We incorporate both automated and manual triage, and provide estimates of the completeness and reliabi…
Spatially Resolved Velocity Structures in Jets of DF Tau and UY Aur A
Principe, David A.; Günther, Hans Moritz; Schneider, P. Christian +1 more
Young stars accrete mass and angular momentum from their circumstellar disks. Some of them also drive outflows, which can be distinguished in optical forbidden emission lines. We analyze a sample of binary T Tauri stars observed with long-slit spectroscopy by the Hubble Space Telescope between 1998 and 2000, searching for spatially resolved outflo…
X-Ray Observations of the Peculiar Cepheid V473 Lyr Identify A Low-mass Companion
Drake, Jeremy J.; Evans, Nancy Remage; Marengo, Massimo +17 more
V473 Lyr is a classical Cepheid that is unique in having substantial amplitude variations with a period of approximately 3.3 yr, thought to be similar to the Blazhko variations in RR Lyrae stars. We obtained an XMM-Newton observation of this star to follow up a previous detection in X-rays. Rather than the X-ray burst and rapid decline near maximu…
A Spectroscopic Classification Survey to Search for New ρ Puppis Stars
Gray, Richard O.; McGahee, Courtney; Griffin, R. E. M. +2 more
The ρ Puppis stars are mid-F-type stars that show peculiar chemical-abundance patterns similar to those of the Am stars. Typically they exhibit overabundances of iron-peak elements such as Fe and Ni and s- and r-process elements such as Sr and Eu, and underabundances of certain other elements including He, Ca, and Sc. It has been proposed that the…
The Quadruple System HIP 45734
Tokovinin, Andrei
HIP 45734 is a quadruple system of 2 + 2 architecture located at 68 pc from the Sun. The outer 9″ system A,B has a period of ∼104 yr. The subsystem Aa,Ab is a visual binary with a period of 20.1 yr and an eccentricity of 0.78. Its periastron in 2019.1 was observed spectroscopically, yielding masses (1.10 ± 0.04 and 0.98 ± 0.03 ${{ \math…
Estimating the Ages of FGK Dwarf Stars through the Use of GALEX FUV Magnitudes
Crandall, Sara; Smith, Graeme H.; Subramonian, Arjun +2 more
Stellar age cannot be directly measured, yet age determinations are fundamental to understanding the evolution of stars, planets, and galaxies. The work presented here builds upon the idea of a stellar-activity age. We utilized far-ultraviolet (FUV) photometry acquired by the Galaxy Evolution Explorer (GALEX) space telescope as an indicator of chr…
Optical Studies of Eight AM Herculis-type Cataclysmic Variable Stars
Thorstensen, John R.; Buckley, David A. H.; Woudt, Patrick A. +2 more
We report detailed follow-up observations of eight cataclysmic variable stars (CVs) that are apparently AM Her stars, also called polars. For all, we either determine orbital periods for the first time or improve on existing determinations. The seven for which we have spectra show the high-amplitude radial-velocity curves and prominent He II λ4686…