planets and satellites: atmospheres; planets and satellites: composition; planets and satellites: gaseous planets; stars: individual: GJ 504
Abstract :
[en] 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. 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 LBTI Exozodi Exoplanet Common Hunt (LEECH) exoplanet imaging survey. By comparing our new photometry and literature photometry with 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 following parameters: T[SUB]eff[/SUB] = 544 ± 10 K, g < 600 m s[SUP]-2[/SUP], [M/H] = 0.60 ± 0.12, cloud opacity parameter of f[SUB]sed[/SUB] = 2-5, R = 0.96 ± 0.07 R[SUB]Jup[/SUB], and log(L) = -6.13 ± 0.03 L[SUB]⊙[/SUB], implying a hot start mass of 3-30 M[SUB]jup[/SUB] for a conservative age range of 0.1-6.5 Gyr. Of particular interest, our model fits suggest that GJ 504 b has a superstellar metallicity. Since planet formation can create objects with nonstellar metallicities, while binary star formation cannot, this result suggests that GJ 504 b formed like a planet, not like a binary companion. The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrophisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota, and University of Virginia.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Skemer, Andrew J.; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA ; University of California, Santa Cruz, 1156 High St. Santa Cruz, CA 95064, USA
Morley, Caroline V.; University of California, Santa Cruz, 1156 High St. Santa Cruz, CA 95064, USA
Zimmerman, Neil T.; Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany ; Princeton University, 4 Ivy Ln, Princeton, NJ 08544, USA ; Space Telescope Science Institute, 3700 San Martin Drive, Baltimore MD 21218, USA
Skrutskie, Michael F.; University of Virginia, 530 McCormick Rd., Charlottesville, VA 22904, USA
Leisenring, Jarron; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Buenzli, Esther; Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
Bonnefoy, Mickael; Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany ; Institut de Planetologie et d’Astrophysique de Grenoble, 414 Rue de la Piscine, 38400 St-Martin d’Heres, France
Bailey, Vanessa; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Hinz, Philip; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Defrere, Denis ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Esposito, Simone; Istituto Nazionale di Astrofisica-Arcetri Astrophysical Observatory, Largo Enrico Fermi 5, 50125, Florence, Italy
Apai, Dániel; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA ; Lunar and Planetary Laboratory, University of Arizona, 1629 East University Blvd, Tucson, AZ 85721, USA
Biller, Beth; Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany ; University of Edinburgh, Old College, South Bridge, Edinburgh Eh8 9YL, UK
Brandner, Wolfgang; Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
Close, Laird; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Crepp, Justin R.; Notre Dame University, 225 Nieuwland Science Hall, Notre Dame, IN 46556, USA
De Rosa, Robert J.; Arizona State University, 781 South Terrace Rd, Tempe, AZ 85281, USA ; University of California, Berkeley, 501 Campbell Hall, Berkeley, CA 94720, USA
Desidera, Silvano; Istituto Nazionale di Astrofisica-Padova Astronomical Observatory, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
Eisner, Josh; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Fortney, Jonathan; University of California, Santa Cruz, 1156 High St. Santa Cruz, CA 95064, USA
Freedman, Richard; Search for Extraterrestrial Intelligence Institute, Mountain View, 189 North Bernardo Ave, Mountain View, CA 94043, USA ; NASA Ames Research Center, Moffett Field, Mountain View, CA 94035, USA
Henning, Thomas; Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
Hofmann, Karl-Heinz; Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, 53121, Bonn, Germany
Kopytova, Taisiya; Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
Lupu, Roxana; NASA Ames Research Center, Moffett Field, Mountain View, CA 94035, USA
Maire, Anne-Lise ; Istituto Nazionale di Astrofisica-Padova Astronomical Observatory, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
Males, Jared R.; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Marley, Mark; NASA Ames Research Center, Moffett Field, Mountain View, CA 94035, USA
Morzinski, Katie; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Oza, Apurva; University of Virginia, 530 McCormick Rd., Charlottesville, VA 22904, USA ; Université Pierre et Marie Curie, 4 Place Jussieu, 75005 Paris, France
Patience, Jenny; Arizona State University, 781 South Terrace Rd, Tempe, AZ 85281, USA
Rajan, Abhijith; Arizona State University, 781 South Terrace Rd, Tempe, AZ 85281, USA
Rieke, George; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Schertl, Dieter; Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, 53121, Bonn, Germany
Schlieder, Joshua; Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany ; NASA Ames Research Center, Moffett Field, Mountain View, CA 94035, USA
Stone, Jordan; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Su, Kate; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Vaz, Amali; Steward Observatory, University of Arizona, 933 North Cherry Ave. Tucson, AZ 85721, USA
Visscher, Channon; Dordt College, 498 4th Ave NE, Sioux Center, IA 51250, USA
Ward-Duong, Kimberly; Arizona State University, 781 South Terrace Rd, Tempe, AZ 85281, USA
Weigelt, Gerd; Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, 53121, Bonn, Germany
Woodward, Charles E.; Minnesota Institute for Astrophysics, University of Minnesota, 106 Pleasant St. SE Minneapolis, MN 55455, USA)
