학술논문
SCExAO/CHARIS Direct Imaging of A Low-Mass Companion At A Saturn-Like Separation from an Accelerating Young A7 Star
Document Type
Working Paper
Author
Chilcote, Jeffrey; Tobin, Taylor; Currie, Thayne; Brandt, Timothy D.; Groff, Tyler D.; Kuzuhara, Masayuki; Guyon, Olivier; Lozi, Julien; Jovanovic, Nemanja; Sahoo, Ananya; Deo, Vincent; Akiyama, Eiji; Janson, Markus; Knapp, Jill; Kwon, Jungmi; McElwain, Michael W.; Nishikawa, Jun; Wagner, Kevin; Hełminiak, Krzysztof; Tamura, Motohide
Source
Subject
Language
Abstract
We present the SCExAO direct imaging discovery and characterization of a low-mass companion to the nearby young A7IV star, HD 91312. SCExAO/CHARIS $JHK$ (1.1-2.4 $\mu m$) spectra and SCExAO/HiCIAO $H$ band imaging identify the companion over a two year baseline in a highly inclined orbit with a maximum projected separation of 8 au. The companion, HD 91312 B, induces an 8.8-$\sigma$ astrometric acceleration on the star as seen with the Gaia & Hipparcos satellites and a long-term radial velocity trend as previously identified by Borgniet et al. (2019). HD 91312 B's spectrum is consistent with that of an early-to-mid M dwarf. Hipparcos and Gaia absolute astrometry, radial-velocity data, and SCExAO/CHARIS astrometry constrain its dynamical mass to be $0.337^{+0.042}_{-0.044}$M$_\odot$, consistent with - but far more precise than - masses derived from spectroscopy, and favors a nearly edge-on orbit with a semi-major axis of $\sim$9.7 au. This work is an example of precisely characterizing properties of low-mass companions at solar system-like scales from a combination of direct imaging, astrometry, and radial-velocity methods.
Comment: 14 pages, 13 figures, Accepted for publication in AJ
Comment: 14 pages, 13 figures, Accepted for publication in AJ