Contributed Talk - Splinter Exoplanets

Thursday, 16 September 2021, 14:45   (virtual Exo)

GJ 832c: an artifact of stellar activity

Paula Gorrini (1,2), Nicola Astudillo-Defru (3), Rodrigo Díaz (4), Christophe Lovis (5), Xavier Bonfils (6), Stefan Dreizler (2), Sandra Jeffers (7), Eloy Rodríguez (8)
(1) Universidad de Concepción, Chile; (2) Georg-August-Universität Göttingen, Germany; (3) Universidad Católica de la Santísima Concepción, Chile; (4) Universidad de Buenos Aires, Argentina; (5) Universitè de Genève, Switzerland; (6) Univ. Grenoble Alpes, France; (7) Max-Planck Institute for Solar System Research, Germany; (8) Instituto de Astrfísica de Andalucía, Spain

Gliese 832 (GJ 832) is a M2V star with two planet candidates detected by radial velocity (RV). The orbital period of the inner planet (35.68 $pm$ 0.03 days) falls into the reported value of the stellar rotation period (45.7 $pm$ 9.3 days), being therefore important to determine its true nature. In this study, we perform a detailed analysis on the RV data, including new observations from HARPS, as well as incorporating photometry data and analysing stellar activity indicators. We re-computed the rotation period by performing a Gaussian process regression (GP) on the S-index, measuring 37.46 $pm$ 1.47 days, in agreement with the reported value but improved by 89.19\%. The photometry data agrees with this new measurement. We analyzed General Lomb-Scargle (GLS) and Stacked Bayesian GLS (sBGLS) Periodograms in order to study the periodicity and stability of the signals on the RV data. We also modelled Keplerians and added GP accounting for stellar activity and conclude that GJ 832c is an artifact of stellar activity.