brown dwarfs; infrared: planetary systems; instrumentation: adaptive optics; planets and satellites: atmospheres; planets and satellites: gaseous planets; stars: individual: HR 8799 2M1207 b
Abstract :
[en] Gas-giant planets emit a large fraction of their light in the mid-infrared (gsim3 μm), where photometry and spectroscopy are critical to our understanding of the bulk properties of extrasolar planets. Of particular importance are the L- and M-band atmospheric windows (3-5 μm), which are the longest wavelengths currently accessible to ground-based, high-contrast imagers. We present binocular LBT adaptive optics (AO) images of the HR 8799 planetary system in six narrow-band filters from 3 to 4 μm, and a Magellan AO image of the 2M1207 planetary system in a broader 3.3 μm band. These systems encompass the five known exoplanets with luminosities consistent with L → T transition brown dwarfs. Our results show that the exoplanets are brighter and have shallower spectral slopes than equivalent temperature brown dwarfs in a wavelength range that contains the methane fundamental absorption feature (spanned by the narrow-band filters and encompassed by the broader 3.3 μm filter). For 2M1207 b, we find that thick clouds and non-equilibrium chemistry caused by vertical mixing can explain the object's appearance. For the HR 8799 planets, we present new models that suggest the atmospheres must have patchy clouds, along with non-equilibrium chemistry. Together, the presence of a heterogeneous surface and vertical mixing presents a picture of dynamic planetary atmospheres in which both horizontal and vertical motions influence the chemical and condensate profiles.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Skemer, Andrew J.; Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
Marley, Mark S.; NASA Ames Research Center, MS-245-3, Moffett Field, CA 94035, USA
Hinz, Philip M.; Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
Morzinski, Katie M. ; Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
Skrutskie, Michael F.; Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904, USA
Leisenring, Jarron M.; Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA ; Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich, Switzerland
Close, Laird M.; Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
Saumon, Didier; Los Alamos National Laboratory, Mail Stop F663, Los Alamos, NM 87545, USA
Bailey, Vanessa P.; Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
Briguglio, Runa; Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 50125 Firenze, Italy
Defrere, Denis ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Esposito, Simone; Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 50125 Firenze, Italy
Follette, Katherine B.; Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
Hill, John M.; Large Binocular Telescope Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
Males, Jared R.; Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
Puglisi, Alfio; Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 50125 Firenze, Italy
Rodigas, Timothy J.; Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA ; Department of Terrestrial Magnetism, Carnegie Institute of Washington, 5241 Broad Branch Road NW, Washington, DC 20015, USA
Xompero, Marco; Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 50125 Firenze, Italy)
