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

TL;DR

This study reports the detection of thermal emission from the hot Jupiter WASP-43b in H and Ks-bands, providing insights into its atmospheric temperature and energy redistribution, and constraining the presence of temperature inversion.

Contribution

First ground-based detection of thermal emission from WASP-43b in multiple bands, with implications for its atmospheric properties and energy redistribution.

Findings

Eclipse depths of 0.103% in H-band and 0.194% in Ks-band.

Atmospheric temperature estimated at ~1850 K, slightly above equilibrium temperature.

Limited day-night energy redistribution, suggesting a lack of strong temperature inversion.

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 CFHT. We obtained a secondary eclipse depth of 0.103$_{-0.017}^{+0.017}%$ and 0.194$_{-0.029}^{+0.029}%$ in the H and Ks-bands, respectively. The Ks band depth is consistent with previous measurement in the narrow band centered at 2.09um by Gillon et al. (2012). 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 $\lesssim 15-25$%, 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.