Ground-based detections of thermal emission from the dense hot jupiter WASP-43b in the H and Ks bands

Abstract

We report new detections of thermal emission from the transiting hot Jupiter WASP-43b in the H and Ks bands as observed at secondary eclipses. The observations were made with the WIRCam instrument on the Canada-France-Hawaii Telescope. We obtained a secondary eclipse depth of 0.103 and 0.194 in the H and Ks bands, respectively. The Ks-band depth is consistent with the previous measurement in the narrow band centered at 2.09 μm by Gillon et al. Our eclipse depths in both bands are consistent with a blackbody spectrum with a temperature of ∼1850 K, slightly higher than the dayside equilibrium temperature without day-night energy redistribution. Based on theoretical models of the dayside atmosphere of WASP-43b, our data constrain the day-night energy redistribution in the planet to be ≲ 15%-25%, depending on the metal content in the atmosphere. Combined with energy balance arguments, our data suggest that a strong temperature inversion is unlikely in the dayside atmosphere of WASP-43b. However, a weak inversion cannot be strictly ruled out at the current time. Future observations are required to place detailed constraints on the chemical composition of the atmosphere. © 2013. The American Astronomical Society. All rights reserved.