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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 709985.0, MPI für Astronomie / Publikationen_mpia
Characterization of the gaseous companion k Andromedae b. New Keck and LBTI high-contrast observations
Authors:Bonnefoy, M.; Currie, T.; Marleau, G. -. D.; Schlieder, J. E.; Wisniewski, J.; Carson, J.; Covey, K. R.; Henning, T.; Biller, B.; Hinz, P.; Klahr, H.; Marsh Boyer, A. N.; Zimmerman, N.; Janson, M.; McElwain, M.; Mordasini, C.; Skemer, A.; Bailey, V.; Defrère, D.; Thalmann, C.; Skrutskie, M.; Allard, F.; Homeier, D.; Tamura, M.; Feldt, M.; Cumming, A.; Grady, C.; Brandner, W.; Helling, C.; Witte, S.; Hauschildt, P.; Kandori, R.; Kuzuhara, M.; Fukagawa, M.; Kwon, J.; Kudo, T.; Hashimoto, J.; Kusakabe, N.; Abe, L.; Brandt, T.; Egner, S.; Guyon, O.; Hayano, Y.; Hayashi, M.; Hayashi, S.; Hodapp, K.; Ishii, M.; Iye, M.; Knapp, G.; Matsuo, T.; Mede, K.; Miyama, M.; Morino, J. -. I.; Moro-Martin, A.; Nishimura, T.; Pyo, T.; Serabyn, E.; Suenaga, T.; Suto, H.; Suzuki, R.; Takahashi, nullval; Takami, M.; Takato, N.; Terada, H.; Tomono, D.; Turner, E.; Watanabe, M.; Yamada, T.; Takami, H.; Usuda, T.
Date of Publication (YYYY-MM-DD):2014
Title of Journal:Astronomy and Astrophysics
Start Page:id. A111 (20 pp)
Audience:Not Specified
Abstract / Description:Context. 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 understanding the formation and evolution of gas giant planets and brown dwarfs on wide orbits. <BR /> Aims: We present new angular differential imaging (ADI) images of the system at 2.146 (Ks), 3.776 (L'), 4.052 (NB_4.05), and 4.78 mum (M') obtained with Keck/NIRC2 and LBTI/LMIRCam, as well as more accurate near-infrared photometry of the star with the MIMIR instrument. We aim to determine the near-infrared spectral energy distribution of the companion and use it to characterize the object. <BR /> Methods: We used analysis methods adapted to ADI to extract the companion flux. We compared the photometry of the object to reference young, and old objects and to a set of seven PHOENIX-based atmospheric models of cool objects accounting for the formation of dust. We used evolutionary models to derive mass estimates considering a wide range of plausible initial conditions. Finally, we used dedicated formation models to discuss the possible origin of the companion. <BR /> Results: 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 detect 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 log 10(L/L&sun;) = -3.76 ± 0.06. Atmospheric models yield Teff = 1900+100-200 K. They do not set any constraint on the surface gravity. "Hot-start" evolutionary models predict masses of 14+25-2 MJup based on the luminosity and temperature estimates, and when considering a conservative age range for the system (30+120-10 Myr), "warm-start" evolutionary tracks constrain the mass to M >= 10MJup. <BR /> Conclusions: The mass of kappa Andromedae b mostly falls in the brown-dwarf regime, owing to remaining uncertainties in age and in mass-luminosity models. According to the formation models, disk instability in a primordial disk may account for the position and a wide range of plausible masses of kappa And b. The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; Instituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of the University of Notre Dame, University of Minnesota, and University of Virginia.Appendices are available in electronic form at <A href="http://www.aanda.org/10.1051/0004-6361/201322119/olm">http://www.aanda.org</A>
Free Keywords:instrumentation: adaptive optics; techniques: photometric; planetary systems; stars: individual: kappa Andromedae
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6361 %R 10.1051/0004-6361/201322119
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