2020/11/17 by Thayne Currie, Timothy D. Brandt, Masayuki Kuzuhara +27 · 1 citation
Physics and Astronomy · #astro-ph.SR #astro-ph.EP #astro-ph.IM
paper · pdf · doi:10.3847/2041-8213/abc631
11 pages, 3 figures, 2 tables; ApJ Letters in press. First discovery from SCExAO/CHARIS; first substellar companion discovered through direct imaging using Gaia for target selection
arxiv created 2020/11/17 · arxiv updated 2020/12/09
We present the direct imaging discovery of a substellar companion to the nearby Sun-like star, HD 33632 Aa, at a projected separation of ∼ 20 au, obtained with SCExAO/CHARIS integral field spectroscopy complemented by Keck/NIRC2 thermal infrared imaging. The companion, HD 33632 Ab, induces a 10.5σ astrometric acceleration on the star as detected with the Gaia and Hipparcos satellites. SCExAO/CHARIS JHK (1.1--2.4 μm) spectra and Keck/NIRC2 L\rm p (3.78 μm) photometry are best matched by a field L/T transition object: an older, higher gravity, and less dusty counterpart to HR 8799 cde. Combining our astrometry with Gaia/Hipparcos data and archival Lick Observatory radial-velocities, we measure a dynamical mass of 46.4 ± 8 M\rm J and an eccentricity of e <0.46 at 95% confidence. HD 33632 Ab's mass and mass ratio (4.0% ± 0.7%) are comparable to the low-mass brown dwarf GJ 758 B and intermediate between the more massive brown dwarf HD 19467 B and the (near-)planet mass companions to HR 2562 and GJ 504. Using Gaia to select for direct imaging observations with the newest extreme adaptive optics systems can reveal substellar or even planet-mass companions on solar system-like scales at an increased frequency compared to blind surveys.