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

Autor: P. Gorrini, N. Astudillo-Defru, S. Dreizler, M. Damasso, R. F. Díaz, X. Bonfils, S. V. Jeffers, J. R. Barnes, F. Del Sordo, J.-M. Almenara, E. Artigau, F. Bouchy, D. Charbonneau, X. Delfosse, R. Doyon, P. Figueira, T. Forveille, C. A. Haswell, M. J. López-González, C. Melo, R. E. Mennickent, G. Gaisné, N. Morales Morales, F. Murgas, F. Pepe, E. Rodríguez, N. C. Santos, L. Tal-Or, Y. Tsapras, S. Udry
Přispěvatelé: Ministerio de Ciencia e Innovación (España), European Commission
Rok vydání: 2022
Předmět:
Zdroj: Astronomy and Astrophysics
Digital.CSIC. Repositorio Institucional del CSIC
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Popis: Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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. © P. Gorrini et al. 2022.
P.G. acknowledges research funding from CONICYT project 22181925. N.A.-D. acknowledges the support of FONDECYT project 3180063. SVJ acknowledges the support of the DFG priority programme SPP 1992 “Exploring the Diversity of Extrasolar Planets (JE 701/5-1). F.D.S. acknowledges support from a Marie Curie Action of the European Union (grant agreement 101030103). R.E.M. gratefully acknowledges support by the ANID BASAL projects ACE210002 and FB210003 and FONDECYT 1190621. Y.T. acknowledges the support of DFG priority program SPP 1992 ‘Exploring the Diversity of Extrasolar Planets” (TS 356/3-1). J.R. Barnes and C.A. Haswell are funded by STFC under consolidated grant ST/T000295/1. We acknowledge financial support from the Spanish Agencia Estatal de Investigación of the Ministerio de Ciencia, Innovación y Universidades through projects PID2019-109522GB-C52, PID2019-107061GB-C64, PID2019-110689RB-100 and the Centre of Excellence ‘Severo Ochoa’ Instituto de Astrofísica de Andalucía (SEV-2017-0709). We acknowledge the support by FCT – Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COM-PETE2020 – Programa Operacional Competitividade e Internacionalização by these grants: UID/FIS/04434/2019; UIDB/04434/2020; UIDP/04434/2020; PTDC/FIS-AST/32113/2017 & POCI-01-0145-FEDER-032113; PTDC/FISAST/28953/2017 & POCI-01-0145-FEDER-028953. This work made use of RadVel (Fulton et al. 2018), Pyaneti (Barragán et al. 2022), MULTINEST V3.10 (e.g. Feroz et al. 2019)), PYMULTINEST wrapper (Buchner et al. 2014), GEORGE (Ambikasaran et al. 2015), and lightkurve (Lightkurve Collaboration 2018). This research includes publicly available data from the Mikulski Archive for Space Telescopes (MAST) from the TESS mission, as well as data public data from HARPS, UCLES and PFS.
Databáze: OpenAIRE
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