Thermal Emission of WASP-14b Revealed with Three Spitzer Eclipses

TL;DR

This study presents Spitzer Space Telescope observations of WASP-14b, revealing its thermal emission, temperature, and orbital characteristics, and discusses implications for its atmospheric composition and energy redistribution.

Contribution

First direct measurement of WASP-14b's thermal emission through multiple Spitzer eclipses, providing insights into its atmospheric properties and orbital eccentricity.

Findings

Eclipse depths of 0.224% at 4.5 μm and 0.181% at 8.0 μm.

Brightness temperatures of approximately 2200 K and 1600 K.

No evidence of a thermal inversion, with limited day-night energy redistribution.

Abstract

Exoplanet WASP-14b is a highly irradiated, transiting hot Jupiter. Joshi et al. calculate an equilibrium temperature Teq of 1866 K for zero albedo and reemission from the entire planet, a mass of 7.3 +/- 0.5 Jupiter masses and a radius of 1.28 +/- 0.08 Jupiter radii. Its mean density of 4.6 g/cm3 is one of the highest known for planets with periods less than 3 days. We obtained three secondary eclipse light curves with the Spitzer Space Telescope. The eclipse depths from the best jointly fit model are $0.224\%$ +/- $0.018\%$ at 4.5 {\mu}m and $0.181\%$ +/- $0.022\%$ at 8.0 {\mu}m. The corresponding brightness temperatures are 2212 +/- 94 K and 1590 +/- 116 K. A slight ambiguity between systematic models suggests a conservative 3.6 {\mu}m eclipse depth of $0.19\%$ +/- $0.01\%$ and brightness temperature of 2242 +/- 55 K. Although extremely irradiated, WASP-14b does not show any distinct evidence of a thermal inversion. In addition, the present data nominally favor models with day night energy redistribution less than $~30\%$. The current data are generally consistent with oxygen-rich as well as carbon-rich compositions, although an oxygen-rich composition provides a marginally better fit. We confirm a significant eccentricity of e = 0.087 +/- 0.002 and refine other orbital parameters.