Search Publications
Precise Dynamical Masses of Directly Imaged Companions from Relative Astrometry, Radial Velocities, and Hipparcos-Gaia DR2 Accelerations
Dupuy, Trent J.; Bowler, Brendan P.; Brandt, Timothy D.
We measure dynamical masses for five objects—three ultracool dwarfs, one low-mass star, and one white dwarf—by fitting orbits to a combination of the Hipparcos-Gaia Catalog of Accelerations, literature radial velocities, and relative astrometry. Our approach provides precise masses without any assumptions about the primary star, even though the ob…
Reference Star Differential Imaging of Close-in Companions and Circumstellar Disks with the NIRC2 Vortex Coronagraph at the W. M. Keck Observatory
Matthews, Keith; Serabyn, Eugene; Absil, Olivier +11 more
Reference star differential imaging (RDI) is a powerful strategy for high-contrast imaging. Using example observations taken with the vortex coronagraph mode of Keck/NIRC2 in L‧ band, we demonstrate that RDI provides improved sensitivity to point sources at small angular separations compared to angular differential imaging (ADI). Applying RDI to i…
Speckle Interferometry at SOAR in 2018
Tokovinin, Andrei; Briceño, Cesar; Horch, Elliott P. +2 more
The results of speckle interferometric observations at the 4.1 m Southern Astrophysical Research Telescope (SOAR) in 2018 are given, totaling 3097 measurements of 2427 resolved pairs with separations from 11 mas to 5.″9 (median 0.″15, magnitude difference up to 7 mag) and nonresolutions of 624 targets. This work continues our long-term speckle pro…
The Mass-Activity Relationships in M and K Dwarfs. I. Stellar Parameters of Our Sample of M and K Dwarfs
Doyle, J. G.; Mullan, D. J.; Butler, C. J. +3 more
Empirical correlations between stellar parameters such as rotation or radius and magnetic activity diagnostics require estimates of the effective temperatures and the stellar radii. The aim of this study is to propose simple methods that can be applied to large samples of stars in order to derive estimates of the stellar parameters. Good empirical…
A Near-coplanar Stellar Flyby of the Planet Host Star HD 106906
Kalas, Paul; De Rosa, Robert J.
We present an investigation into the kinematics of HD 106906 using the newly released Gaia DR2 catalog to search for close encounters with other members of the Scorpius-Centaurus (Sco-Cen) association. HD 106906 is an eccentric spectroscopic binary that hosts both a large asymmetric debris disk extending out to at least 500 au and a directly image…
A Discrete Set of Possible Transit Ephemerides for Two Long-period Gas Giants Orbiting HIP 41378
Omohundro, Mark; Vanderburg, Andrew; Hellier, Coel +22 more
In 2015, K2 observations of the bright (V = 8.9, K = 7.7) star HIP 41378 revealed a rich system of at least five transiting exoplanets, ranging in size from super-Earths to gas giants. The 2015 K2 observations only spanned 74.8 days, and the outer three long-period planets in the system were only detected with a single transit, so their orbital pe…
Two Jovian Planets around the Giant Star HD 202696: A Growing Population of Packed Massive Planetary Pairs around Massive Stars?
Trifonov, Trifon; Stock, Stephan; Henning, Thomas +6 more
We present evidence for a new two-planet system around the giant star HD 202696 (=HIP 105056, BD +26 4118). The discovery is based on public HIRES radial velocity (RV) measurements taken at Keck Observatory between 2007 July and 2014 September. We estimate a stellar mass of {1.91}-0.14+0.09{M}⊙ for HD 202696, whic…
Speckle Observations and Orbits of Multiple Stars
Torres, Guillermo; Latham, David W.; Tokovinin, Andrei +2 more
We report results of speckle-interferometric monitoring of visual hierarchical systems using the newly commissioned instrument NN-EXPLORE Exoplanet and Stellar Speckle Imager at the 3.5 m WIYN telescope. During one year, 390 measurements of 129 resolved subsystems were made, while some targets were unresolved. Using our astrometry and archival dat…
Spectroscopic Orbits of Subsystems in Multiple Stars. V.
Tokovinin, Andrei
Spectroscopic orbits are determined for inner subsystems in nine stellar hierarchies (HIP 2863, 4974, 8353, 28796, 35261, 92929, 115272, 115552, and 117596). Their periods range from 2.5 to 312 days. For each system, estimates of masses, orbital inclination, and other parameters are given.
The Possible Astrometric Signature of a Planetary-mass Companion to the Nearby Young Star TW Piscis Austrini (Fomalhaut B): Constraints from Astrometry, Radial Velocities, and Direct Imaging
Esposito, Thomas M.; Kalas, Paul; De Rosa, Robert J. +5 more
We present constraints on the presence of substellar companions to the nearby (d ∼ 7.6 pc) young (440 ± 40 Myr) K4Ve star TW Piscis Austrini, the wide (∼0.3 pc) companion to the A4V star Fomalhaut. We combined absolute astrometry from Hipparcos and Gaia with literature radial velocity measurements and dedicated high-contrast imaging observations o…