Scexao/Charis near-infrared direct imaging, spectroscopy, and forward-modeling of k And B: A likely young, low-gravity superjovian companion

Thayne Currie, Timothy D. Brandt, Taichi Uyama, Eric L. Nielsen, Sarah Blunt, Olivier Guyon, Motohide Tamura, Christian Marois, Kyle Mede, Masayuki Kuzuhara, Tyler D. Groff, Nemanja Jovanovic, N. Jeremy Kasdin, Julien Lozi, Klaus Hodapp, Jeffrey Chilcote, Joseph Carson, Frantz Martinache, Sean Goebel, Carol GradyMichael McElwain, Eiji Akiyama, Ruben Asensio-Torres, Masa Hayashi, Markus Janson, Gillian R. Knapp, Jungmi Kwon, Jun Nishikawa, Daehyeon Oh, Joshua Schlieder, Eugene Serabyn, Michael Sitko, Nour Skaf

Research output: Contribution to journalArticlepeer-review


We present SCExAO/CHARIS high-contrast imaging/JHK integral field spectroscopy of k And b, a directly-imaged low-mass companion orbiting a nearby B9V star. We detect k 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 et al. (2016). k And bfs spectrum best resembles that of a low-gravity L0.L1 dwarf (L0.L1). Its spectrum and luminosity are very well matched by 2MASSJ0141-4633 and several other 12.5.15 MJ 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 MJ), 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 k And b down to ∼ 0.ŒŒ3 (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 starfs rotation axis. However, k And bfs semimajor axis is plausibly larger than 75 au and in a region where disk instability could form massive companions. Deeper k 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 k And bfs chemistry and whether its spectrum provides an insight into its formation environment.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Oct 22 2018


  • Planetary systems
  • stars: Early-type
  • stars: Individual: HD 222439-stars: Individual (HD 222439)
  • techniques: High angular resolution

ASJC Scopus subject areas

  • General

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