Detailed stellar activity analysis and modelling of GJ 832: Reassessment of the putative habitable zone planet GJ 832c

• Autores: Gorrini, Antoni Pablo; Astudillo Defru, Nicola; Dreizler, S.; Damasso, M.; Díaz, Rodrigo Fernando; Bonfils, X.; Jeffers, S.V.; Barnes, J.R.; Del Sordo, F.; Almenara, J.-M.; Artigau, E.; Bouchy, F.; Charbonneau, D.; Delfosse, X.; Doyon, R.; Figueira, P.; Forveille, T.; Haswell, C.A.; López González, M.J.; Melo, C.; Mennickent, R. E.; Gaisné, G.; Morales, N. Morales; Murgas, F.; Pepe, F.; Rodríguez, E.; Santos, N.C.; Tal-Or, L.; Tsapras, Y.; Udry, Sebastian Pablo
• Año de publicación: 2022
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: PLANETARY SYSTEMS; STARS: ACTIVITY; STARS: INDIVIDUAL: GJ 832; TECHNIQUES: PHOTOMETRIC; TECHNIQUES: RADIAL VELOCITIES
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Context. Gliese-832 (GJ 832) is an M2V star hosting a massive planet on a decade-long orbit, GJ 832b, discovered by radial velocity (RV). Later, a super Earth or mini-Neptune orbiting within the stellar habitable zone was reported (GJ 832c). The recently determined stellar rotation period (45.7 ± 9.3 days) is close to the orbital period of putative planet c (35.68 ± 0.03 days). Aims. We aim to confirm or dismiss the planetary nature of the RV signature attributed to GJ 832c, by adding 119 new RV data points, new photometric data, and an analysis of the spectroscopic stellar activity indicators. Additionally, we update the orbital parameters of the planetary system and search for additional signals. Methods. We performed a frequency content analysis of the RVs to search for periodic and stable signals. Radial velocity time series were modelled with Keplerians and Gaussian process (GP) regressions alongside activity indicators to subsequently compare them within a Bayesian framework. Results. We updated the stellar rotational period of GJ 832 from activity indicators, obtaining 37.5+1.4-1.5 days, improving the precision by a factor of 6. The new photometric data are in agreement with this value. We detected an RV signal near 18 days (FAP < 4.6%), which is half of the stellar rotation period. Two Keplerians alone fail at modelling GJ 832b and a second planet with a 35-day orbital period. Moreover, the Bayesian evidence from the GP analysis of the RV data with simultaneous activity indices prefers a model without a second Keplerian, therefore negating the existence of planet c.
Fil: Gorrini, Antoni Pablo. Universidad de Concepción; Chile. Universität Göttingen; Alemania
Fil: Astudillo Defru, Nicola. Universidad Católica de la Santísima Concepción; Chile
Fil: Dreizler, S.. Universität Göttingen; Alemania
Fil: Damasso, M.. Istituto Nazionale di Astrofisica; Italia
Fil: Díaz, Rodrigo Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Físicas. - Universidad Nacional de San Martín. Instituto de Ciencias Físicas; Argentina
Fil: Bonfils, X.. Universite Grenoble Alpes; Francia
Fil: Jeffers, S.V.. Max Planck Institute For Solar System Research; Alemania
Fil: Barnes, J.R.. The Open University (ou); Reino Unido
Fil: Del Sordo, F.. Osservatorio Astrofisico Di Catania; España. Consejo Superior de Investigaciones Científicas; España
Fil: Almenara, J.-M.. Universite Grenoble Alpes; Francia
Fil: Artigau, E.. Institut de Recherche Sur Les Exoplanètes; Canadá. University of Montreal; Canadá
Fil: Bouchy, F.. Universidad de Ginebra; Suiza
Fil: Charbonneau, D.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos
Fil: Delfosse, X.. Universite Grenoble Alpes; Francia
Fil: Doyon, R.. Institut de Recherche Sur Les Exoplanètes; Canadá. University of Montreal; Canadá
Fil: Figueira, P.. European Southern Observatory Santiago; Chile. Universidad de Porto; Portugal
Fil: Forveille, T.. Universite Grenoble Alpes; Francia
Fil: Haswell, C.A.. The Open University (ou); Reino Unido
Fil: López González, M.J.. Consejo Superior de Investigaciones Científicas; España
Fil: Melo, C.. Portuguese Space Agency; Portugal
Fil: Mennickent, R. E.. Universidad de Concepción; Chile
Fil: Gaisné, G.. Universite Grenoble Alpes; Francia
Fil: Morales, N. Morales. Consejo Superior de Investigaciones Científicas; España
Fil: Murgas, F.. Instituto Astrofisico de Canarias; España. Universidad de La Laguna; España
Fil: Pepe, F.. Universidad de Ginebra; Suiza
Fil: Rodríguez, E.. Instituto de Astrofísica de Andalucía; España
Fil: Santos, N.C.. Universidad de Porto; Portugal
Fil: Tal-Or, L.. Ariel University; Israel
Fil: Tsapras, Y.. Ruprecht Karls Universitat Heidelberg; Alemania
Fil: Udry, Sebastian Pablo. Universidad de Ginebra; Suiza