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Title: Spitzer and z' secondary eclipse observations of the highly irradiated transiting brown dwarf KELT-1b

We present secondary eclipse observations of the highly irradiated transiting brown dwarf KELT-1b. These observations represent the first constraints on the atmospheric dynamics of a highly irradiated brown dwarf, the atmospheres of irradiated giant planets at high surface gravity, and the atmospheres of brown dwarfs that are dominated by external, rather than internal, energy. Using the Spitzer Space Telescope, we measure secondary eclipse depths of 0.195% ± 0.010% at 3.6 μm and 0.200% ± 0.012% at 4.5 μm. We also find tentative evidence for the secondary eclipse in the z' band with a depth of 0.049% ± 0.023%. These measured eclipse depths are most consistent with an atmosphere model in which there is a strong substellar hotspot, implying that heat redistribution in the atmosphere of KELT-1b is low. While models with a more mild hotspot or even with dayside heat redistribution are only marginally disfavored, models with complete heat redistribution are strongly ruled out. The eclipse depths also prefer an atmosphere with no TiO inversion layer, although a model with TiO inversion is permitted in the dayside heat redistribution case, and we consider the possibility of a day-night TiO cold trap in this object. For the first time, we comparemore » the IRAC colors of brown dwarfs and hot Jupiters as a function of effective temperature. Importantly, our measurements reveal that KELT-1b has a [3.6] – [4.5] color of 0.07 ± 0.11, identical to that of isolated brown dwarfs of similarly high temperature. In contrast, hot Jupiters generally show redder [3.6] – [4.5] colors of ∼0.4, with a very large range from ∼0 to ∼1. Evidently, despite being more similar to hot Jupiters than to isolated brown dwarfs in terms of external forcing of the atmosphere by stellar insolation, KELT-1b appears to have an atmosphere most like that of other brown dwarfs. This suggests that surface gravity is very important in controlling the atmospheric systems of substellar mass bodies.« less
Authors:
;  [1] ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ; ;  [9]
  1. Department of Astronomy, The Ohio State University, 140 W. 18th Ave., Columbus, OH 43210 (United States)
  2. Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292 (United States)
  3. Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
  4. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)
  5. Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States)
  6. Lunar and Planetary Laboratory, 1629 E. University Blvd., University of Arizona, Tucson, AZ (United States)
  7. Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Santa Barbara, CA 93117 (United States)
  8. Department of Physics, Lehigh University, Bethlehem, PA 18015 (United States)
  9. Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States)
Publication Date:
OSTI Identifier:
22351572
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 783; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATMOSPHERES; COLD TRAPS; COLOR; COMPARATIVE EVALUATIONS; DWARF STARS; ECLIPSE; GRAVITATION; INSOLATION; IRRADIATION; JUPITER PLANET; LAYERS; LIMITING VALUES; MASS; SPACE; TELESCOPES; TITANIUM OXIDES