Detecting phasecurves in the K2 data

Abstract

Exoplanets are planets orbiting stars other than our Sun. During their motion around their star, due to gravitational effects, and due to the planet’s thermal and reflective radiation, small variations in the lightcurve could be detected (Esteves et al. 2015). Phasecurves are small-scale variations in planetary flux that arise from an exoplanet’s motion around its host star. If detected, the phasecurve can lead to determining the planet’s mass, its albedo, and it can give us an idea about its atmosphere. In this work we aim to detect these variations in the data from the K2 mission. To do this we first test two different models on two already published phasecurves detected in the K2 data (Malavolta 2018), (Močnik et al. 2018). We reveal the failure of one of the models (Serrano 2018) to recover a phasecurve for a planet with a relatively low mass having a lightcurve that posses a signal with a significant noise, while the other one (Faigler and Mazeh 2011) succeeds in recovering the phasecurve of the same planet. We also uncover significant modulations in the data of K2 31-b, which resulted in finding the planet’s mass and its geometric albedo.