Detection of the Occultation of 55 Cancri e with TESS

Abstract

55 Cancri e is an ultra-short period transiting Super-Earth observed by TESS in Sector 21. Using this photometry, we measure the occultation depth in the TESS bandpass, leveraging the precise transit light curve and comparing multiple detrending methods. We measure the occultation depth to be $(15.0\pm4.8)$ppm - a staggeringly small change in brightness, yet one detected by TESS in just a single sector of data. This implies a brightness temperature of $2800_{-160}^{+130}$K, which is around 1.5$\sigma$ greater than expected given the mean depth measured with Spitzer. This is not a formally significant difference, and may be accounted for by the known variability, or by an albedo of ~0.5. In any case, future TESS observations of this system will provide an exciting opportunity to further study this diminutive world's atmosphere.