The Astronomical Journal, 154:232 (8pp), 2017 December https://doi.org/10.3847/1538-3881/aa9278 © 2017. The American Astronomical Society. All rights reserved. A Case for an Atmosphere on Super-Earth 55 Cancri e Isabel Angelo1,2 and Renyu Hu1,3 1 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA;
[email protected] 2 Department of Astronomy, University of California, Campbell Hall, #501, Berkeley CA, 94720, USA 3 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA Received 2017 August 2; revised 2017 October 6; accepted 2017 October 8; published 2017 November 16 Abstract One of the primary questions when characterizing Earth-sized and super-Earth-sized exoplanets is whether they have a substantial atmosphere like Earth and Venus or a bare-rock surface like Mercury. Phase curves of the planets in thermal emission provide clues to this question, because a substantial atmosphere would transport heat more efficiently than a bare-rock surface. Analyzing phase-curve photometric data around secondary eclipses has previously been used to study energy transport in the atmospheres of hot Jupiters. Here we use phase curve, Spitzer time-series photometry to study the thermal emission properties of the super-Earth exoplanet 55 Cancri e. We utilize a semianalytical framework to fit a physical model to the infrared photometric data at 4.5 μm. The model uses parameters of planetary properties including Bond albedo, heat redistribution efficiency (i.e., ratio between radiative timescale and advective timescale of the atmosphere), and the atmospheric greenhouse factor.