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Machine-learning Regression of Extinction in the Second Gaia Data Release
Bai, Yu; Wang, Song; Liu, JiFeng +1 more
Machine learning has become a popular tool to help us make better decisions and predictions, based on experiences, observations, and analyzing patterns, within a given data set without explicit functions. In this paper, we describe an application of the supervised machine-learning algorithm to the extinction regression for the second Gaia data rel…
Subaru Near-infrared Imaging Polarimetry of Misaligned Disks around the SR 24 Hierarchical Triple System
Henning, Thomas; Nakagawa, Takao; Terada, Hiroshi +66 more
The SR 24 multistar system hosts both circumprimary and circumsecondary disks, which are strongly misaligned with each other. The circumsecondary disk is circumbinary in nature. Interestingly, both disks are interacting, and they possibly rotate in opposite directions. To investigate the nature of this unique twin disk system, we present 0.″1 reso…
Calibrating the Galactic Cepheid Period-Luminosity Relation from the Maximum-likelihood Technique
Lazovik, Yaroslav A.; Rastorguev, Alexey S.
We present a realization of the maximum-likelihood technique, which is one of the latest modifications of the Baade-Becker-Wesselink method. Our approach is based on nonlinear calibrations of the effective temperature and bolometric correction, which take into account metallicity and surface gravity. It allows one to estimate the key Cepheid param…
Visual Orbits of Spectroscopic Binaries with the CHARA Array. III. HD 8374 and HD 24546
Gies, Douglas R.; Lester, Kathryn V.; Monnier, John D. +9 more
We present the visual orbits of two long-period spectroscopic binary stars, HD 8374 and HD 24546, using interferometric observations acquired with the CHARA Array and the Palomar Testbed Interferometer. We also obtained new radial velocities from echelle spectra using the APO 3.5 m and Fairborn 2.0 m telescopes. By combining the visual and spectro…
Robustly Detecting Changes in Warm Jupiters' Transit Impact Parameters
Dawson, Rebekah I.
Torques from a mutually inclined perturber can change a transiting planet's impact parameter, resulting in variations in the transit shape and duration. Detection of and upper limits on changes in impact parameter yield valuable constraints on a planetary system's three-dimensional architecture. Constraints for warm Jupiters are particularly inter…
Discovery of a Nearby Young Brown Dwarf Disk
Debes, John H.; Kiman, Rocio; Schneider, Adam C. +16 more
We report the discovery of the youngest brown dwarf with a disk at 102 pc from the Sun, WISEA J120037.79-784508.3 (W1200-7845), via the Disk Detective citizen science project. We establish that W1200-7845 is located in the ${3.7}_{-1.4}^{+4.6}$ Myr old ɛ Cha association. Its spectral energy distribution (SED) exhibits clear evidence of an infrared…
A Wide-orbit Exoplanet OGLE-2012-BLG-0838Lb
Soszyński, I.; Udalski, A.; Szymański, M. K. +50 more
We present the discovery of a planet on a very wide orbit in the microlensing event OGLE-2012-BLG-0838. The signal of the planet is well separated from the main peak of the event and the planet-star projected separation is found to be twice the Einstein ring radius, which corresponds to a projected separation of ≈4 au. Similar planets around low-m…
Magnetic Inflation and Stellar Mass. V. Intensification and Saturation of M-dwarf Absorption Lines with Rossby Number
Muirhead, Philip S.; Mann, Andrew W.; Newton, Elisabeth R. +2 more
In young Sun-like stars and field M-dwarf stars, chromospheric and coronal magnetic activity indicators such as Hα, X-ray, and radio emission are known to saturate with low Rossby number (Ro ≲ 0.1), defined as the ratio of rotation period to convective turnover time. The mechanism for the saturation is unclear. In this paper, we use photospheric T…
A High Angular Resolution Survey of Massive Stars in Cygnus OB2: JHK Adaptive Optics Results from the Gemini Near-Infrared Imager
Goodwin, S. P.; Gies, D. R.; ten Brummelaar, T. A. +8 more
We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the Near-Infrared Imager camera and ALTAIR adaptive optics system of the Gemini North telescope. We observed 74 O- and early-B-type stars in Cyg OB2 in the JHK infrared bands in order to detect binary and multiple compani…
A Search for Polarized Thermal Emission from Directly Imaged Exoplanets and Brown Dwarf Companions to Nearby Stars
Jensen-Clem, Rebecca; De Rosa, Robert J.; Hinkley, Sasha +15 more
Aerosols in the atmospheres of cloudy gas giant exoplanets and brown dwarfs scatter and polarize these objects' thermal emission. If such an object has an oblate shape or nonuniform cloud distribution, the net degree of linear polarization can show an increase ranging from several tenths of a percent to a few percent. Modern high-contrast imaging …