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Characterization of the gaseous companion κ Andromedae b

2013; EDP Sciences; Volume: 562; Linguagem: Inglês

10.1051/0004-6361/201322119

1432-0746

M. Bonnefoy, Thayne Currie, Gabriel-Dominique Marleau, Joshua E. Schlieder, John P. Wisniewski, J. Carson, Kevin R. Covey, Thomas Henning, Beth Biller, Philip M. Hinz, Hubert Klahr, A. N. Marsh Boyer, Neil T. Zimmerman, M. Janson, Michael W. McElwain, C. Mordasini, Andrew Skemer, Vanessa P. Bailey, Denis Defrère, C. Thalmann, Michael F. Skrutskie, F. Allard, D. Homeier, Motohide Tamura, M. Feldt, A. Cumming, C. A. Grady, W. Brandner, Ch. Helling, S. Witte, P. H. Hauschildt, Ryo Kandori, Masayuki Kuzuhara, Misato Fukagawa, Jungmi Kwon, Tomoyuki Kudo, Jun Hashimoto, Nobuhiko Kusakabe, L. Abe, Timothy D. Brandt, Sebastian Egner, Olivier Guyon, Yutaka Hayano, Masahiko Hayashi, Saeko S. Hayashi, K. W. Hodapp, Miki Ishii, Masanori Iye, G. R. Knapp, Taro Matsuo, Kyle Mede, M. Miyama, J. I. Morino, Amaya Moro‐Martín, T. Nishimura, Tae‐Soo Pyo, Eugene Serabyn, Takuya Suenaga, Hiroshi Suto, Ryuji Suzuki, Takahashi Takahashi, M. Takami, N. Takato, Hiroshi Terada, D. Tomono, Edwin L. Turner, Makoto Watanabe, Tōru Yamada, Hideki Takami, Tomonori Usuda,

Astro and Planetary Science

We previously reported the direct detection of a low mass companion at a projected separation of 55+-2 AU around the B9 type star {\kappa} Andromedae. The properties of the system (mass ratio, separation) make it a benchmark for the understanding of the formation and evolution of gas giant planets and brown dwarfs on wide-orbits. We present new angular differential imaging (ADI) images of the Kappa Andromedae system at 2.146 (Ks), 3.776 (L'), 4.052 (NB 4.05) and 4.78 {\mu}m (M') obtained with Keck/NIRC2 and LBTI/LMIRCam, as well as more accurate near-infrared photometry of the star with the MIMIR instrument. We derive a more accurate J = 15.86 +- 0.21, H = 14.95 +- 0.13, Ks = 14.32 +- 0.09 mag for {\kappa} And b. We redetect the companion in all our high contrast observations. We confirm previous contrasts obtained at Ks and L' band. We derive NB 4.05 = 13.0 +- 0.2 and M' = 13.3 +- 0.3 mag and estimate Log10(L/Lsun) = -3.76 +- 0.06. We build the 1-5 microns spectral energy distribution of the companion and compare it to seven PHOENIX-based atmospheric models in order to derive Teff = 1900+100-200 K. Models do not set constrains on the surface gravity. ``Hot-start" evolutionary models predict masses of 14+25-2 MJup based on the luminosity and temperature estimates, and considering a conservative age range for the system (30+120-10 Myr). ``warm-start" evolutionary tracks constrain the mass to M >= 11 MJup. Therefore, the mass of {\kappa} Andromedae b mostly falls in the brown-dwarf regime, due to remaining uncertainties in age and mass-luminosity models. According to the formation models, disk instability in a primordial disk could account for the position and a wide range of plausible masses of {\kappa} And b.