Characterization of the gaseous companion κ Andromedae b: New Keck and LBTI high-contrast observations
Creators: name: Bonnefoy, M.
name: Currie, T.
name: Marleau, G. -D.
name: Schlieder, J. E.
name: Wisniewski, J.
name: Carson, J.
name: Covey, K. R.
name: Henning, T.
name: Biller, B.
name: Hinz, P.
name: Klahr, H.
name: Boyer, A. N. Marsh
name: Zimmerman, N.
name: Janson, M.
name: McElwain, M.
name: Mordasini, C.
name: Skemer, A.
name: Bailey, V.
name: Defrère, D.
name: Thalmann, C.
name: Skrutskie, M.
name: Allard, F.
name: Homeier, D.
name: Tamura, M.
name: Feldt, M.
name: Cumming, A.
name: Grady, C.
name: Brandner, W.
name: Kandori, R.
name: Kuzuhara, M.
name: Fukagawa, M.
name: Kwon, J.
name: Kudo, T.
name: Hashimoto, J.
name: Kusakabe, N.
name: Abe, L.
name: Brandt, T.
name: Egner, S.
name: Guyon, O.
name: Hayano, Y.
name: Hayashi, M.
name: Hayashi, S.
name: Hodapp, K.
name: Ishii, M.
name: Iye, M.
name: Knapp, G.
name: Matsuo, T.
name: Mede, K.
name: Miyama, M.
name: Morino, J. -I.
name: Moro-Martin, A.
name: Nishimura, T.
name: Pyo, T.
name: Serabyn, E.
name: Suenaga, T.
name: Suto, H.
name: Suzuki, R.
name: Takahashi
name: Takami, M.
name: Takato, N.
name: Terada, H.
name: Tomono, D.
name: Turner, E.
name: Watanabe, M.
name: Yamada, T.
name: Takami, H.
name: Usuda, T.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We previously reported the direct detection of a low mass companion at a projected separation of 55+-2 AU around the B9 type star κ 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 μm (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 κ 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 &gt;= 11 MJup. Therefore, the mass of κ 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 κ And b.
description: 20 pages, 16 figures, accepted for publication in Astronomy and Astrophysics on August 6, 2013