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Spitzer and z' Secondary Eclipse Observations of the Highly Irradiated Transiting Brown Dwarf KELT-1b

Beatty, Thomas G. and Collins, Karen A. and Fortney, Jonathan and Knutson, Heather and Gaudi, B. Scott and Bruns, Jacob M. and Showman, Adam P. and Eastman, Jason and Pepper, Joshua and Siverd, Robert J. and Stassun, Keivan G. and Kielkopf, John F. (2014) Spitzer and z' Secondary Eclipse Observations of the Highly Irradiated Transiting Brown Dwarf KELT-1b. Astrophysical Journal, 783 (2). Art. No. 112. ISSN 0004-637X.

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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 compare 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Beatty, Thomas G.0000-0002-9539-4203
Collins, Karen A.0000-0001-6588-9574
Fortney, Jonathan0000-0002-9843-4354
Knutson, Heather0000-0002-0822-3095
Gaudi, B. Scott0000-0003-0395-9869
Eastman, Jason0000-0003-3773-5142
Pepper, Joshua0000-0002-3827-8417
Siverd, Robert J.0000-0001-5016-3359
Stassun, Keivan G.0000-0002-3481-9052
Additional Information:© 2014 American Astronomical Society. Received 2013 October 28; accepted 2014 January 23; published 2014 February 21. Work by T.G.B. and B.S.G. was partially supported by NSF CAREER grant AST-1056524. K.A.C. was supported by a NASA Kentucky Space Grant Consortium Graduate Fellowship. This research has made use of NASA’s Astrophysics Data System.
Funding AgencyGrant Number
Kentucky Space Grant ConsortiumUNSPECIFIED
Subject Keywords:binaries: eclipsing; planetary systems; techniques: photometric
Issue or Number:2
Record Number:CaltechAUTHORS:20140617-133017021
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Official Citation:Spitzer and z' Secondary Eclipse Observations of the Highly Irradiated Transiting Brown Dwarf KELT-1b Thomas G. Beatty et al. 2014 ApJ 783 112
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46310
Deposited By: Ruth Sustaita
Deposited On:17 Jun 2014 21:12
Last Modified:09 Mar 2020 13:19

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