Thermal Emission and Tidal Heating of the Heavy and Eccentric Planet XO-3b
Pavel Machalek, Tom Greene, Peter R. McCullough, Adam Burrows,, Christopher J. Burke, Joseph L. Hora, Christopher M. Johns-Krull, Drake L., Deming

TL;DR
This study measures the infrared flux ratios of XO-3b, confirming a thermal inversion likely caused by high stellar irradiation, and estimates its orbital eccentricity and tidal heating effects.
Contribution
First detailed infrared flux measurements of XO-3b across four IRAC bands, confirming a thermal inversion and constraining its orbital eccentricity and tidal heating parameters.
Findings
XO-3b exhibits a thermal inversion consistent with high stellar irradiation.
Orbital eccentricity of XO-3b is estimated at e = 0.277 ± 0.009.
Tidal heating is significant in explaining XO-3b's inflated radius.
Abstract
We determined the flux ratios of the heavy and eccentric planet XO-3b to its parent star in the four IRAC bands of the Spitzer Space Telescope: 0.101% +- 0.004% at 3.6 micron; 0.143% +- 0.006% at 4.5 micron; 0.134% +- 0.049% at 5.8 micron and 0.150% +- 0.036% at 8.0 micron. The flux ratios are within [-2.2,0.3, -0.8, -1.7]-sigma of the model of XO-3b with a thermally inverted stratosphere in the 3.6 micron, 4.5 micron, 5.8 micron and 8.0 micron channels, respectively. XO-3b has a high illumination from its parent star (Fp ~(1.9 - 4.2) x 10^9 ergs cm^-2 s^-1) and is thus expected to have a thermal inversion, which we indeed observe. When combined with existing data for other planets, the correlation between the presence of an atmospheric temperature inversion and the substellar flux is insufficient to explain why some high insolation planets like TrES-3 do not have stratospheric…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
