학술논문
SCExAO/CHARIS Near-Infrared Direct Imaging, Spectroscopy, and Forward-Modeling of kappa And b: A Likely Young, Low-Gravity Superjovian Companion
Document Type
Working Paper
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; Jovanovic, Nemanja; Kasdin, N. Jeremy; Lozi, Julien; Hodapp, Klaus W.; Chilcote, Jeffrey; Carson, Joseph; Martinache, Frantz; Goebel, Sean; Grady, Carol; McElwain, Michael; Akiyama, Eiji; Asensio-Torres, Ruben; Hayashi, Masa; Janson, Markus; Knapp, Gillian; Kwon, Jungmi; Nishikawa, Jun; Oh, Daehyeon; Schlieder, Joshua; Serabyn, Eugene; Sitko, Michael; Skaf, Nour
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Abstract
We present SCExAO/CHARIS high-contrast imaging/$JHK$ integral field spectroscopy of $\kappa$ And b, a directly-imaged low-mass companion orbiting a nearby B9V star. We detect $\kappa$ 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). $\kappa$ And b's spectrum best resembles that of a low-gravity L0--L1 dwarf (L0--L1$\gamma$). 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 ($q$ $\sim$ 0.005$^{+0.005}_{-0.001}$). We did not unambiguously identify additional, more closely-orbiting companions brighter and more massive than $\kappa$ And b down to $\rho$ $\sim$ 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, $\kappa$ And b's semimajor axis is plausibly larger than 75 au and in a region where disk instability could form massive companions. Deeper $\kappa$ 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 $\kappa$ And b's chemistry and whether its spectrum provides an insight into its formation environment.
Comment: 27 pages, 15 Figures, 6 Tables, 4 Appendices. Accepted for publication in AJ. Provides evidence reestablishing kappa And b as a directly-imaged planet
Comment: 27 pages, 15 Figures, 6 Tables, 4 Appendices. Accepted for publication in AJ. Provides evidence reestablishing kappa And b as a directly-imaged planet