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Spitzer secondary eclipses of Qatar-1b

Garhart, Emily and Deming, Drake and Mandell, Avi and Knutson, Heather and Fortney, Jonathan J. (2018) Spitzer secondary eclipses of Qatar-1b. Astronomy and Astrophysics, 610 . Art. No. A55. ISSN 0004-6361. doi:10.1051/0004-6361/201731637.

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Aims. Previous secondary eclipse observations of the hot Jupiter Qatar-1b in the Ks band suggest that it may have an unusually high day side temperature, indicative of minimal heat redistribution. There have also been indications that the orbit may be slightly eccentric, possibly forced by another planet in the system. We investigate the day side temperature and orbital eccentricity using secondary eclipse observations with Spitzer. Methods. We observed the secondary eclipse with Spitzer/IRAC in subarray mode, in both 3.6 and 4.5 μm wavelengths. We used pixel-level decorrelation to correct for Spitzer’s intra-pixel sensitivity variations and thereby obtain accurate eclipse depths and central phases. Results. Our 3.6 μm eclipse depth is 0.149 ± 0.051% and the 4.5 μm depth is 0.273 ± 0.049%. Fitting a blackbody planet to our data and two recent Ks band eclipse depths indicates a brightness temperature of 1506 ± 71 K. Comparison to model atmospheres for the planet indicates that its degree of longitudinal heat redistribution is intermediate between fully uniform and day-side only. The day side temperature of the planet is unlikely to be as high (1885 K) as indicated by the ground-based eclipses in the Ks band, unless the planet’s emergent spectrum deviates strongly from model atmosphere predictions. The average central phase for our Spitzer eclipses is 0.4984 ± 0.0017, yielding e cos ω = −0.0028 ± 0.0027. Our results are consistent with a circular orbit, and we constrain e cos ω much more strongly than has been possible with previous observations.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Deming, Drake0000-0001-5727-4094
Mandell, Avi0000-0002-8119-3355
Knutson, Heather0000-0002-0822-3095
Fortney, Jonathan J.0000-0002-9843-4354
Additional Information:© 2018 ESO. Article published by EDP Sciences. Received 25 July 2017; Accepted 29 November 2017; Published online 27 February 2018.
Group:Astronomy Department
Subject Keywords:planets and satellites: atmosphere
Record Number:CaltechAUTHORS:20180329-112358083
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Official Citation:Spitzer secondary eclipses of Qatar-1b. Emily Garhart, Drake Deming, Avi Mandell, Heather Knutson and Jonathan J. Fortney. A&A, 610 (2018) A55. DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85497
Deposited By: Tony Diaz
Deposited On:29 Mar 2018 19:36
Last Modified:15 Nov 2021 20:29

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