SPITZER OBSERVATIONS OF THE THERMAL EMISSION FROM WASP-43b

Hellier

Abstract

WASP-43b is one of the closest-orbiting hot Jupiters, with a semimajor axis of a = 0.01526 ± 0.00018 AU and a period of only 0.81 days. However, it orbits one of the coolest stars with a hot Jupiter (T * = 4520 ± 120 K), giving the planet a modest equilibrium temperature of T eq = 1440 ± 40 K, assuming zero Bond albedo and uniform planetary energy redistribution. The eclipse depths and brightness temperatures from our jointly fit model are 0.347% ± 0.013% and 1670 ± 23 K at 3.6 µm and 0.382% ± 0.015% and 1514 ± 25 K at 4.5 µm. The eclipse timings improved the estimate of the orbital period, P, by a factor of three (P = 0.81347436 ± 1.4 × 10–7 days) and put an upper limit on the eccentricity ($e = 0.010^{+0.010}_{-0.007}$). We use our Spitzer eclipse depths along with four previously reported ground-based photometric observations in the near-infrared to constrain the atmospheric properties of WASP-43b. The data rule out a strong thermal inversion in the dayside atmosphere of WASP-43b. Model atmospheres with no thermal inversions and fiducial oxygen-rich compositions are able to explain all the available data. However, a wide range of metallicities and C/O ratios can explain the data. The data suggest low day-night energy redistribution in the planet, consistent with previous studies, with a nominal upper limit of about 35% for the fraction of energy incident on the dayside that is redistributed to the nightside.

Citation

Hellier. (2014). SPITZER OBSERVATIONS OF THE THERMAL EMISSION FROM WASP-43b. Astrophysical Journal, https://doi.org/10.1088/0004-637X/781/2/116

• Acceptance Date: Feb 27, 2013
• Publication Date: Jan 16, 2014
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Publisher: American Astronomical Society
• DOI: https://doi.org/10.1088/0004-637X/781/2/116
• Keywords: eclipses; planets and satellites; atmospheres; WASP-43b; photometric
• Publisher URL: https://doi.org/10.1088/0004-637x/781/2/116