1-2.4 mu m Near-IR Spectrum of the Giant Planet beta Pictoris b Obtained with the Gemini Planet Imager
ASTRONOMICAL JOURNAL
Authors: Chilcote, Jeffrey; Pueyo, Laurent; De Rosa, Robert J.; Vargas, Jeffrey; Macintosh, Bruce; Bailey, Vanessa P.; Barman, Travis; Bauman, Brian; Bruzzone, Sebastian; Bulger, Joanna; Burrows, Adam S.; Cardwell, Andrew; Chen, Christine H.; Cotten, Tara; Dillon, Daren; Doyon, Rene; Draper, Zachary H.; Duchene, Gaspard; Dunn, Jennifer; Erikson, Darren; Fitzgerald, Michael P.; Follette, Katherine B.; Gavel, Donald; Goodsell, Stephen J.; Graham, James R.; Greenbaum, Alexandra Z.; Hartung, Markus; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn; Larkin, James E.; Maire, Jerome; Marchis, Franck; Marley, Mark S.; Marois, Christian; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Morzinski, Katie M.; Nielsen, Eric L.; Norton, Andrew; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Perrin, Marshall; Poyneer, Lisa; Rajan, Abhijith; Rameau, Julien; Rantakyroe, Fredrik T.; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Schneider, Adam C.; Serio, Andrew; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Wang, Jason J.; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler
Abstract
Using the Gemini Planet Imager located at Gemini South, we measured the near-infrared (1.0-2.4 mu m) spectrum of the planetary companion to the nearby, young star beta. Pictoris. We compare the spectrum obtained with currently published model grids and with known substellar objects and present the best matching models as well as the best matching observed objects. Comparing the empirical measurement of the bolometric luminosity to evolutionary models, we find a mass of 12.9. +/- 0.2. M-Jup, an effective temperature of 1724. +/- 15 K, a radius of 1.46. +/- 0.01. R-Jup, and a surface gravity of log g = 4.18. 0.01 [dex] (cgs). The stated uncertainties are statistical errors only, and do not incorporate any uncertainty on the evolutionary models. Using atmospheric models, we find an effective temperature of 1700-1800 K and a surface gravity of log g = 3.5-4.0 [dex] depending upon the model. These values agree well with other publications and with "hot-start" predictions from planetary evolution models. Further, we find that the spectrum of beta Pic. b best matches a low surface gravity L2. +/- 1 brown dwarf. Finally, comparing the spectrum to field brown dwarfs, we find the the spectrum best matches 2MASS J04062677- 381210 and 2MASS J03552337 + 1133437.
2MASS J13243553+6358281 Is an Early T-type Planetary-mass Object in the AB Doradus Moving Group
ASTROPHYSICAL JOURNAL LETTERS
Authors: Gagne, Jonathan; Allers, Katelyn N.; Theissen, Christopher A.; Faherty, Jacqueline K.; Gagliuffi, Daniella Bardalez; Artigau, Etienne
Abstract
We present new radial velocity and trigonometric distance measurements indicating that the unusually red and photometrically variable T2 dwarf 2MASS. J13243553+6358281 is a member of the young (similar to 150 Myr) AB. Doradus moving group (ABDMG) based on its space velocity. We estimate its model-dependent mass in the range 11-12M(Jup) at the age of the ABDMG, and its trigonometric distance of 12.7 +/- 1.5 pc makes it one of the nearest known isolated planetary-mass objects. The unusually red continuum of 2MASS J13243553+6358281 in the near-infrared was previously suspected to be caused by an unresolved L + T brown dwarf binary, although it was never observed with high spatial resolution imaging. This new evidence of youth suggests that a low surface gravity may be sufficient to explain this peculiar feature. Using the new parallax we find that its absolute J-band magnitude is similar to 0.4 mag fainter than equivalent-type field brown dwarfs, suggesting that the binary hypothesis is unlikely. The fundamental properties of 2MASS J13243553+6358281 follow the spectral type sequence of other known high-likelihood members of the ABDMG. The effective temperature of 2MASS J13243553+6358281 provides the first precise constraint on the L/T transition at a known young age and indicates that it happens at a temperature of similar to 1150 K at similar to 150 Myr, compared to similar to 1250 K for field brown dwarfs.
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