Spitzer Secondary Eclipses of Qatar-1b

Abstract

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. We observed the secondary eclipse with Spitzer/IRAC in subarray mode, in both 3.6 and 4.5 micron wavelengths. We used pixel-level decorrelation to correct for Spitzer's intra-pixel sensitivity variations and thereby obtain accurate eclipse depths and central phases. Our 3.6 micron eclipse depth is 0.149 +/- 0.051% and the 4.5 micron 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 +/- 71K. 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 (1885K) 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(omega) = -0.0028 +/- 0.0027. Our results are consistent with a circular orbit, and we constrain e cos(omega) much more strongly than has been possible with previous observations.

References in corpus (7)

• Detection of Thermal Emission from an Extrasolar Planet
• Spitzer Secondary Eclipses of the Dense, Modestly-irradiated, Giant Exoplanet HAT-P-20b Using Pixel-Level Decorrelation
• Near-infrared Thermal Emission Detections of a number of hot Jupiters and the Systematics of Ground-based Near-infrared Photometry
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• No variations in transit times for Qatar-1 b
• Detection of the secondary eclipse of Qatar-1b in the Ks band

Cited by in corpus (7)

• Statistical Characterization of Hot Jupiter Atmospheres using Spitzer's Secondary Eclipses
• A New Analysis of 8 Spitzer Phase Curves and Hot Jupiter Population Trends: Qatar-1b, Qatar-2b, WASP-52b, WASP-34b, and WASP-140b
• Probing Transit Timing Variation and its Possible Origin with Twelve New Transits of TrES-3b
• Characterization of Exoplanets: Secondary Eclipses
• ThERESA: Three-Dimensional Eclipse Mapping with Application to Synthetic JWST Data
• Smaller than expected bright-spot offsets in Spitzer phase curves of the hot Jupiter Qatar-1b
• How to Characterize the Atmosphere of a Transiting Exoplanet