Smaller than Expected Bright-spot Offsets in Spitzer Phase Curves of the Hot Jupiter Qatar-1b

Media type: E-Article
Title: Smaller than Expected Bright-spot Offsets in Spitzer Phase Curves of the Hot Jupiter Qatar-1b
Contributor: Keating, Dylan; Stevenson, Kevin B.; Cowan, Nicolas B.; Rauscher, Emily; Bean, Jacob L.; Bell, Taylor; Dang, Lisa; Deming, Drake; Désert, Jean-Michel; Feng, Y. Katherina; Fortney, Jonathan J.; Kataria, Tiffany; Kempton, Eliza M.-R.; Lewis, Nikole; Line, Michael R.; Mansfield, Megan; May, Erin; Morley, Caroline; Showman, Adam P.
imprint: American Astronomical Society, 2020
Published in: The Astronomical Journal
Language: Not determined
DOI: 10.3847/1538-3881/ab83f4
ISSN: 1538-3881; 0004-6256
Keywords: Space and Planetary Science ; Astronomy and Astrophysics
Origination:
Footnote:
Description: <jats:title>Abstract</jats:title> <jats:p>We present Spitzer full-orbit thermal phase curves of the hot Jupiter Qatar-1b, a planet with the same equilibrium temperature—and intermediate surface gravity and orbital period—as the well-studied planets HD 209458b and WASP-43b. We measure secondary eclipse depths of 0.21 ± 0.02% at 3.6 <jats:italic>μ</jats:italic>m and 0.30 ± 0.02% at 4.5 <jats:italic>μ</jats:italic>m, corresponding to dayside brightness temperatures of <jats:inline-formula> <jats:tex-math> <?CDATA ${1542}_{-31}^{+32}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ajab83f4ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> K and <jats:inline-formula> <jats:tex-math> <?CDATA ${1557}_{-36}^{+35}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ajab83f4ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> K, respectively, consistent with a vertically isothermal dayside. The respective nightside brightness temperatures are <jats:inline-formula> <jats:tex-math> <?CDATA ${1117}_{-71}^{+76}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ajab83f4ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:inline-formula> <jats:tex-math> <?CDATA ${1167}_{-74}^{+69}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ajab83f4ieqn4.gif" xlink:type="simple" /> </jats:inline-formula> K, in line with a trend that hot Jupiters all have similar nightside temperatures. We infer a Bond albedo of <jats:inline-formula> <jats:tex-math> <?CDATA ${0.12}_{-0.16}^{+0.14}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ajab83f4ieqn5.gif" xlink:type="simple" /> </jats:inline-formula> and a moderate day–night heat recirculation efficiency, similar to HD 209458b. General circulation models for HD 209458b and WASP-43b predict that their bright spots should be shifted east of the substellar point by tens of degrees, and these predictions were previously confirmed with Spitzer full-orbit phase curve observations. The phase curves of Qatar-1b are likewise expected to exhibit eastward offsets. Instead, the observed phase curves are consistent with no offset: 11° ± 7° at 3.6 <jats:italic>μ</jats:italic>m and −4° ± 7° at 4.5 <jats:italic>μ</jats:italic>m. The discrepancy in circulation patterns between these three otherwise similar planets points to the importance of secondary parameters like rotation rate and surface gravity, and the presence or absence of clouds, in determining atmospheric conditions on hot Jupiters.</jats:p>
Access State: Open Access

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