Authors

Andrew J. Skemer, University of Arizona
Caroline V. Morley, University of California, Santa Cruz
Neil T. Zimmerman, Max Planck Institute for Astronomy
Michael F. Skrutskie, University of Virginia
Jarron Leisenring, University of Arizona
Esther Buenzli, Max Planck Institute for Astronomy
Mickael Bonnefoy, Max Planck Institute for Astronomy
Vanessa Bailey, University of Arizona
Philip Hinz, University of Arizona
Denis Defrere, University of Arizona
Simone Esposito, Istituto Nazionale di Astrofisica
Daniel Apai, University of Arizona
Beth Biller, The University of Edinburgh
Wolfgang Brandner, Max Planck Institute for Astronomy
Laird Close, University of Arizona
Justin R. Crepp, Notre Dame University, Indiana
Robert J. De Rosa, Arizona State University at the Tempe Campus
Silvano Desidera, Instituto Nazionale di Astrofisica
Josh Eisner, University of Arizona
Jonathan Fortney, University of California, Santa Cruz
Richard Freedman, NASA Ames Research Center
Thomas Henning, Max Planck Institute for Astronomy
Karl-Heinz Hofmann, Max Planck Institute for Radio Astronomy
Taisiya Kopytova, Max Planck Institute for Astronomy
Roxana Lupu, NASA Ames Research Center
Anne-Lise Maire, Instituto Nazionale di Astrofisica
Jared R. Males, University of Arizona
Mark Marley, NASA Ames Research Center
Katie Morzinski, University of Arizona
Apurva Oza, University of Virginia
Jenny Patience, Arizona State University at the Tempe Campus
Abhijith Rajan, Arizona State University at the Tempe Campus
George Rieke, University of Arizona
Dieter Schertl, Max Planck Institute for Radio Astronomy
Joshua Schlieder, NASA Ames Research Center
Jordan Stone, University of Arizona
Kate Su, University of Arizona
Amali Vaz, University of Arizona
Channon Visscher, Dordt CollegeFollow
Kimberly Ward-Duong, Arizona State University at the Tempe Campus
Gerd Weigelt, Max Planck Institute for Radio Astronomy
Charles E. Woodward, University of Minnesota - Twin Cities

Document Type

Article

Publication Date

2-2016

Department

Physics and Astronomy

Keywords

planets, satellites, atmospheres, stars

Abstract

As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly-imaged exoplanets were all L-type. Recently, Kuzuhara et al. (2013) announced the discovery of GJ 504 b, the first T dwarf exoplanet. GJ 504 b provides a unique opportunity to study the atmosphere of a new type of exoplanet with a ∼500 K temperature that bridges the gap between the first directly imaged planets (∼1000 K) and our own Solar System’s Jupiter (∼130 K). We observed GJ 504 b in three narrow L-band filters (3.71, 3.88, and 4.00 µm), spanning the red end of the broad methane fundamental absorption feature (3.3 µm) as part of the LEECH exoplanet imaging survey. By compar-ing our new photometry and literature photometry to a grid of custom model atmospheres, we were able to fit GJ 504 b’s unusual spectral energy distribution for the first time. We find that GJ 504 b is well-fit by models with the follow-ing parameters: Teff =544±10 K, g/s2, [M/H]=0.60±0.12, cloud opacity parameter of fsed = 2 − 5, R=0.96±0.07 RJup, and log(L)=-6.13±0.03 L⊙, im-plying a hot start mass of 3-30 Mjup for a conservative age range of 0.1-6.5 Gyr. Of particular interest, our model fits suggest that GJ 504 b has a super-stellar metallicity. Since planet formation can create objects with non-stellar metal-licities, while binary star formation cannot, this result suggests that GJ 504 b formed like a planet, not like a binary companion.

Comments

Copyright © Astrophysical Journal 2016

Source Publication Title

Astrophysical Journal

Publisher

American Astronomical Society

Volume

817

Issue

2

First Page

166

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