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Dynamical and Atmospheric Characterization of the Substellar Companion HD 33632 Ab from Direct Imaging, Astrometry, and Radial-velocity Data
Currie, Thayne; Tamura, Motohide; Kuzuhara, Masayuki +17 more
We present follow-up SCExAO/CHARIS H- and K-band (R ∼ 70) high-contrast integral field spectroscopy and Keck/NIRC2 photometry of directly imaged brown dwarf companion HD 33632 Ab and new radial-velocity data for the system from the SOPHIE spectrograph, complemented by Hipparcos and Gaia astrometry. These data enable more robust spectral characteri…
SCExAO/CHARIS Spectroscopic Characterization of Cloudy L/T Transition Companion Brown Dwarf HIP 93398 B
Jensen-Clem, Rebecca; Salama, Maïssa; Lewis, Briley L. +10 more
Brown dwarfs with measured dynamical masses and spectra from direct imaging are benchmarks that anchor substellar atmosphere cooling and evolution models. We present Subaru SCExAO/CHARIS infrared spectroscopy of HIP 93398 B, a brown dwarf companion recently discovered by Y. Li et al. (2023), as part of an informed survey using the Hipparcos–Gaia C…
Astrometric Accelerations as Dynamical Beacons: A Giant Planet Imaged inside the Debris Disk of the Young Star AF Lep
Jensen-Clem, Rebecca; Crepp, Justin R.; Zhou, Yifan +13 more
We present the direct-imaging discovery of a giant planet orbiting the young star AF Lep, a 1.2 M ⊙ member of the 24 ± 3 Myr β Pic moving group. AF Lep was observed as part of our ongoing high-contrast imaging program targeting stars with astrometric accelerations between Hipparcos and Gaia that indicate the presence of substellar compa…
Direct-imaging Discovery and Dynamical Mass of a Substellar Companion Orbiting an Accelerating Hyades Sun-like Star with SCExAO/CHARIS
Currie, Thayne; Kwon, Jungmi; Tamura, Motohide +33 more
We present the direct-imaging discovery of a substellar companion in orbit around a Sun-like star member of the Hyades open cluster. So far, no other substellar companions have been unambiguously confirmed via direct imaging around main-sequence stars in Hyades. The star HIP 21152 is an accelerating star as identified by the astrometry from the Ga…
RR Lyrae-based Distances for 39 Nearby Dwarf Galaxies Calibrated to Gaia eDR3
El-Badry, Kareem; Weisz, Daniel R.; Nagarajan, Pranav
We provide uniform RR Lyrae-based distances to 39 dwarf galaxies in and around the Local Group. We determine distances based on a Bayesian hierarchical model that uses periods and magnitudes of published RR Lyrae in dwarf galaxies and is anchored to well-studied Milky Way (MW) RR Lyrae with spectroscopic metallicities and Gaia eDR3 parallaxes. Gai…
Dynamical Masses of the Primary Be Star and Secondary sdB Star in the Single-lined Binary κ Dra (B6 IIIe)
Gies, Douglas R.; Wang, Luqian; Klement, Robert +16 more
Because many classical Be stars may owe their nature to mass and angular-momentum transfer in a close binary, the present masses, temperatures, and radii of their components are of high interest for comparison to stellar evolution models. Object κ Dra is a 61.5 day single-lined binary with a B6 IIIe primary. With the CHARA Array instruments MIRC/M…
The Orbits and Dynamical Masses of the Castor System
Torres, Guillermo; Klement, Robert; Monnier, John D. +12 more
Castor is a system of six stars in which the two brighter objects, Castor A and B, revolve around each other every ~450 yr and are both short-period spectroscopic binaries. They are attended by the more distant Castor C, which is also a binary. Here we report interferometric observations with the Center for High Angular Resolution Astronomy (CHARA…
The First Dynamical Mass Measurement in the HR 8799 System
Dupuy, Trent J.; Brandt, Timothy D.; Brandt, G. Mirek +2 more
HR 8799 hosts four directly imaged giant planets, but none has a mass measured from first principles. We present the first dynamical mass measurement in this planetary system, finding that the innermost planet HR 8799 e has a mass of ${9.6}_{-1.8}^{+1.9}\,{M}_{\mathrm{Jup}}$ . This mass results from combining the well-characterized orbits of all f…
The McDonald Accelerating Stars Survey (MASS): Discovery of a Long-period Substellar Companion Orbiting the Old Solar Analog HD 47127
Cochran, William D.; Endl, Michael; Crepp, Justin R. +12 more
Brown dwarfs with well-determined ages, luminosities, and masses provide rare but valuable tests of low-temperature atmospheric and evolutionary models. We present the discovery and dynamical mass measurement of a substellar companion to HD 47127, an old (≈7-10 Gyr) G5 main-sequence star with a mass similar to the Sun. Radial velocities of the hos…
X-Ray AGB Stars in the 4XMM-DR9 Catalog: Further Evidence for Companions
Guerrero, M. A.; Ortiz, R.
Single AGB stars are not normally expected to be X-ray emitters due to the lack of a corona capable of powering a hot plasma. Therefore, the detection of X-ray emission in AGB stars by the ROSAT, Chandra, and XMM-Newton observatories has been interpreted as evidence for binarity. The number of X-ray-emitting AGB stars is, however, very small, and …