2018/10/22 by Thayne Currie, Timothy D. Brandt, Taichi Uyama +30 · 1 citation
Physics and Astronomy · #astro-ph.EP #astro-ph.IM #astro-ph.SR
paper · pdf · doi:10.3847/1538-3881/aae9ea
27 pages, 15 Figures, 6 Tables, 4 Appendices. Accepted for publication in AJ. Provides evidence reestablishing kappa And b as a directly-imaged planet
arxiv created 2018/10/22 · arxiv updated 2018/12/05
We present SCExAO/CHARIS high-contrast imaging/JHK integral field spectroscopy of κ And b, a directly-imaged low-mass companion orbiting a nearby B9V star. We detect κ And b at a high signal-to-noise and extract high precision spectrophotometry using a new forward-modeling algorithm for (A-)LOCI complementary to KLIP-FM developed by Pueyo (2016). κ And b's spectrum best resembles that of a low-gravity L0--L1 dwarf (L0--L1γ). Its spectrum and luminosity are very well matched by 2MASSJ0141-4633 and several other 12.5--15 M\rm J free floating members of the 40 Myr-old Tuc-Hor Association, consistent with a system age derived from recent interferometric results for the primary, a companion mass at/near the deuterium-burning limit (13+12-2 M\rm J), and a companion-to-primary mass ratio characteristic of other directly-imaged planets (q ∼ 0.005+0.005-0.001). We did not unambiguously identify additional, more closely-orbiting companions brighter and more massive than κ And b down to ρ ∼ 0.3" (15 au). SCExAO/CHARIS and complementary Keck/NIRC2 astrometric points reveal clockwise orbital motion. Modeling points towards a likely eccentric orbit: a subset of acceptable orbits include those that are aligned with the star's rotation axis. However, κ And b's semimajor axis is plausibly larger than 75 au and in a region where disk instability could form massive companions. Deeper κ And high-contrast imaging and low-resolution spectroscopy from extreme AO systems like SCExAO/CHARIS and higher resolution spectroscopy from Keck/OSIRIS or, later, IRIS on the Thirty Meter Telescope could help clarify κ And b's chemistry and whether its spectrum provides an insight into its formation environment.