Spitzer observations of the thermal emission from WASP-43b

Jasmina Blecic, Joseph Harrington, Nikku Madhusudhan, Kevin B. Stevenson, Ryan A. Hardy, Patricio E. Cubillos, Matthew Hardin, Oliver Bowman, Sarah Nymeyer, David R. Anderson, Coel Hellier, Alexis M. S. Smith, Andrew Collier Cameron

Research output: Contribution to journalArticlepeer-review

72 Citations (Scopus)

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 Teq = 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 and0.382% ± 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.

Original languageEnglish
Article number116
Number of pages11
JournalAstrophysical Journal
Volume781
Issue number2
Early online date16 Jan 2014
DOIs
Publication statusPublished - 1 Feb 2014

Keywords

  • Eclipses
  • Planets and satellites: atmospheres
  • Planets and satellites: individual: WASP-43b
  • Techniques: photometric

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