* Astronomy

Members Login

Post Info

TOPIC: Kappa Andromedae

Blobrana

L

Posts: 131433

Date: Apr 2 16:34 2015

HD 222439	Permalink

Title: The Water Abundance of the Directly Imaged Substellar Companion And b Retrieved from a Near Infrared Spectrum Author: Kamen O. Todorov, Michael R. Line, Jaime E. Pineda, Michael R. Meyer, Sascha P. Quanz, Sasha Hinkley, Jonathan J. Fortney Recently, spectral retrieval has proven to be a powerful tool for constraining the physical properties and atmospheric compositions of extrasolar planet atmospheres from observed spectra, primarily for transiting objects but also increasingly for directly imaged planets and brown dwarfs. Despite its strengths, this approach has been applied to only about a dozen targets. Determining the abundances of the main carbon and oxygen-bearing compounds in a planetary atmosphere can lead to the C/O ratio of the object, which is crucial in understanding its formation and migration history. We present a retrieval analysis on the published near-infrared spectrum of {\kappa} And b, a directly imaged substellar companion to a young B9 star. We fit the emission spectrum model utilizing a Markov Chain Monte Carlo algorithm. We estimate the abundance of water vapour, and its uncertainty, in the atmosphere of the object. We also place upper limits on the abundances of carbon dioxide and methane and constrain the pressure-temperature profile of the atmosphere. We compare our results to studies that have applied model retrieval on multiband photometry and emission spectroscopy of hot Jupiters (extrasolar giant planets with orbital periods of several days) and the directly imaged giant planet HR 8799b. We find that the water abundances of the hot Jupiters and the two directly imaged planets inhabit overlapping regions of parameter space and that their P-T profiles are qualitatively similar, despite the wide range of effective temperatures and incident stellar fluxes for these objects. Read more (52kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Nov 20 09:02 2012

Kappa Andromedae b	Permalink

Astronomers Directly Image Massive Star's 'Super-Jupiter' Astronomers using infrared data from the Subaru Telescope in Hawaii have discovered a "super-Jupiter" around the bright star Kappa Andromedae, which now holds the record for the most massive star known to host a directly imaged planet or lightweight brown dwarf companion. Designated Kappa Andromedae b (Kappa And b, for short), the new object has a mass about 12.8 times greater than Jupiter's. This places it teetering on the dividing line that separates the most massive planets from the lowest-mass brown dwarfs. That ambiguity is one of the object's charms, say researchers, who call it a super-Jupiter to embrace both possibilities. Read more __________________

Blobrana

L

Posts: 131433

Date: Nov 20 01:26 2012

Kappa Andromedae	Permalink

Title: Direct Imaging Discovery of a 'Super-Jupiter' Around the late B-Type Star Kappa And Authors: J. Carson, C. Thalmann, M. Janson, T. Kozakis, M. Bonnefoy, B. Biller, J. Schlieder, T. Currie, M. McElwain, M. Goto, T. Henning, W. Brandner, M. Feldt, R. Kandori, M. Kuzuhara, L. Stevens, P. Wong, K. Gainey, M. Fukagawa, Y. Kuwada, T. Brandt, J. Kwon, L. Abe, S. Egner, C. Grady, O. Guyon, J. Hashimoto, Y. Hayano, M. Hayashi, S. Hayashi, K. Hodapp, M. Ishii, M. Iye, G. Knapp, T. Kudo, N. Kusakabe, T. Matsuo, S. Miyama, J. Morino, A. Moro-Martin, T. Nishimura, T. Pyo, E. Serabyn, H. Suto, R. Suzuki, M. Takami, N. Takato, H. Terada, E. Turner, M. Watanabe, J. Wisniewski, T. Yamada, H. Takami, T. Usuda, M. Tamura We present the direct imaging discovery of an extrasolar planet, or possible low-mass brown dwarf, at a projected separation of 55 ±2 AU (1.058 ±0.007 arcsec) from the B9-type star Kappa And. The planet was detected with Subaru/HiCIAO during the SEEDS survey, and confirmed as a bound companion via common proper motion measurements. Observed near-infrared magnitudes of J = 16.3 ±0.3, H = 15.2 ±0.2, Ks = 14.6 ±0.4, and L' = 13.12 ±0.09 indicate a temperature of ~1700 K. The galactic kinematics of the host star are consistent with membership in the Columba association, implying a corresponding age of 30 +20 -10 Myr. The system age, combined with the companion photometry, points to a model-dependent companion mass ~12.8 Jupiter masses. The host star's estimated mass of 2.4-2.5 solar masses places it among the most massive stars ever known to harbour an extrasolar planet or low-mass brown dwarf. While the mass of the companion is close to the deuterium burning limit, its mass ratio, orbital separation, and likely planet-like formation scenario imply that it may be best defined as a 'Super-Jupiter' with properties similar to other recently discovered companions to massive stars. Read more (437kb, PDF) __________________

Page 1 of 1 sorted by

Create your own FREE Forum
Report Abuse