1–2.4 μm Near-IR Spectrum of the Giant Planet β Pictoris b Obtained with the Gemini Planet Imager

Creators: Chilcote, Jeffrey; Millar-Blanchaer, Maxwell A.

Abstract

Using the Gemini Planet Imager located at Gemini South, we measured the near-infrared (1.0–2.4 μm) spectrum of the planetary companion to the nearby, young star β 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 β 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.

Additional Information

© 2017 The American Astronomical Society. Received 2017 January 2; revised 2017 February 27; accepted 2017 February 27; published 2017 March 28. We thank the anonymous referee for the helpful comments that improved the quality of this work. The authors would like to acknowledge the financial support of the Gemini Observatory, the Dunlap Institute, University of Toronto, the NSF Center for Adaptive Optics at UC Santa Cruz, the NSF (AST-0909188; AST-1211562, AST-1405505), NASA Origins (NNX11AD21G; NNX10AH31G, NNX14AC21G, NNX15AC89G), and NASA NExSS (NNX15AD95G), the University of California Office of the President (LFRP-118057), and the Science and Technology Facilities Council (ST/H002707/1). Portions of this work were performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and under contract with the California Institute of Technology/Jet Propulsion Laboratory funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. This work is supported by the NASA Exoplanets Research Program (XRP) by cooperative agreement NNX16AD44G. Support for this work was provided by NASA through Hubble Fellowship grant 51378.01-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. This work benefited from NASAs Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASAs Science Mission Directorate. This research has benefited from the SpeX Prism Library (and/or SpeX Prism Library Analysis Toolkit), maintained by Adam Burgasser at http://www.browndwarfs.org/spexprism, the IRTF Spectral Library, maintained by Michael Cushing, and the Montreal Brown Dwarf and Exoplanet Spectral Library, maintained by Jonathan Gagné. Facility: Gemini South (GPI).

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