학술논문
SCExAO/CHARIS Near-Infrared Direct Imaging, Spectroscopy, and Forward-Modeling of κ and b: A Likely Young, Low-Gravity Superjovian Companion
Document Type
Report
Author
Currie, Thayne; Brandt, Timothy D; Uyama, Taichi; Nielsen, Eric L; Blunt, Sarah; Guyon, Olivier; Tamura, Motohide; Marois, Christian; Mede, Kyle; Kuzuhara, Masayuki; Groff, Tyler D; Jovanovic, Nemanja; Kasdin, N. Jeremy; Lozi, Julien; Hodapp, Klaus; Chilcote, Jeffrey; Carson, Joseph; Martinache, Frantz; Goebel, Sean; Grady, Carol; McElwain, Michael; Akiyama, Eiji; Asensio-Torres, Ruben; Hayashi, Masa; Janson, Markus; Knapp, Gillian R; Kwon, Jungmi; Nishikawa, Jun; Oh, Daehyeon; Schlieder, Joshua; Serabyn, Eugene; Sitko, Michael; Skaf, Nour
Source
The Astrophysical Journal. 156(6)
Subject
Language
English
ISSN
1538-3881
0004-6256
0004-6256
Abstract
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 ratio and extract high-precision spectrophotometry using a new forward-modeling algorithm for (A-)LOCI complementary to KLIP-FM developed by Pueyo et al. 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 2MASS J0141-4633 and several other 12.5–15 M(sub 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(sup +12, sub -2) M(sub J)), and a companion-to-primary mass ratio characteristic of other directly imaged planets (q ∼ 0.005(sup +0.005, sub -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 toward 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 55 au and in a region where disk instability could form massive companions. Deeper high-contrast imaging of κ And and low-resolution spectroscopy from extreme adaptive optics systems such as SCExAO/CHARIS and higher-resolution spectroscopy from Keck/OSIRIS or, later, IRIS on the Thirty Meter Telescope could help to clarify κ And b’s chemistry and whether its spectrum provides an insight into its formation environment.