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; Brandt, Timothy D.; Li, Yiting; Chilcote, Jeffrey; Guyon, Olivier; Lozi, Julien; Bouchy, Francois; Tobin, Taylor; Groff, Tyler D.; Vievard, Sebastien; Deo, Vincent; Skaf, Nour; Boisse, Isabelle; Kasdin, N. Jeremy; El Morsy, Mona; Bovie, Danielle; Lacy, Brianna; Dykes, Erica
United States, Japan, Switzerland, France
Abstract
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 characterization compared to lower-resolution spectra from the discovery paper and more than double the available astrometric and radial-velocity baseline. HD 33632 Ab's spectrum is well reproduced by a field L8.5–L9.5 dwarf. Using the Exo-REM atmosphere models, we derive a best-fit temperature, surface gravity, and radius of Teff = 1250 K, log(g) = 5, and R = 0.97 RJ, respectively, as well as a solar C/O ratio. Adding the SOPHIE radial-velocity data enables far tighter constraints on the companion's orbital properties (e.g., i =