GQ Lup Ab Visible & Near-Infrared Photometric Analysis

Journal Article · Mon Aug 07 04:00:00 EDT 2006 · The Astrophysical Journal Letters, vol. 654, no. 2, January 1, 2007, L151-L154

OSTI ID:902331

Marois, C; Macintosh, B; Barman, T

We have re-analyzed archival HST R and I band images and Subaru CH{sub 4}, H, Ks and L{prime} data of the recently discovered planetary mass companion (PMC) GQ Lup Ab. With these we produce the first R and I band photometry of the companion and fit a radius and effective temperature using detailed model atmospheres. We find an effective temperature of 2338 {+-} 100K, and a radius of 0.37 {+-} 0.05R{sub {circle_dot}} and luminosity of log(L/L{sub {circle_dot}}) = -2.43 {+-} 0.07 (at 140pc). Since we fit wavelengths that span most of the emitted radiation from GQ Lup this luminosity estimate is robust, with uncertainty dominated by the distance uncertainty. The radius obtained for 140pc (0.37R{sub {circle_dot}}) is significantly larger than the one originally derived. The mass of the object is much more model-dependent than the radiative properties, but for the GAIA dusty models we find a mass between 9-20 M{sub Jup}, in the range of the brown dwarf and PMC deuterium burning boundary. Assuming a distance of 140pc, observations fit to 1{sigma} the Baraffe evolution model for a {approx} 15 M{sub Jup} brown dwarf. Additionally, the F606W photometric band is significantly overluminous compared to model predictions. Such overluminosity could be explained by a bright H{alpha} emission from chromospheric activity, interaction with another undetected companion, or accretion. Assuming that GQ Lup Ab has a bright H{alpha} emission line, its H{alpha} emission strength is 10{sup -1.71 {+-} 0.10} L{sub bol}, significantly larger than field late-type dwarfs. GQ Lup Ab might be strongly accreting and still be in its formation phase.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 902331
• Report Number(s): UCRL-JRNL-223503
• Journal Information: The Astrophysical Journal Letters, vol. 654, no. 2, January 1, 2007, L151-L154, Journal Name: The Astrophysical Journal Letters, vol. 654, no. 2, January 1, 2007, L151-L154 Journal Issue: 2 Vol. 654
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS
DEUTERIUM
LUMINOSITY
PHOTOMETRY
RADIATIONS
WAVELENGTHS