J/A+A/658/A115ivo://CDS.VizieR/J/A+A/658/A115doi:10.26093/cds/vizier.36580115CDSFaria J.P.Suarez Mascareno A.Figueira P.Silva A.M.Damasso M.,Demangeon O.Pepe F.Santos N.C.Rebolo R.Cristiani S.Adibekyan V.,Alibert Y.Allart R.Barros S.C.C.Cabral A.D'Odorico V.,Di Marcantonio P.Dumusque X.Ehrenreich D.Gonzalez Hernandez J.I.,Hara N.Lillo-Box J.Lo Curto G.Lovis C.Martins C.J.A.P.Megevand D.,Mehner A.Micela G.Molaro P.Nunes N.J.Palle E.Poretti E.,Sousa S.G.Sozzetti A.Tabernero H.Udry S.Zapatero Osorio M.R.2022-10-12T08:49:28Z2022-02-21T12:44:49ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frdwarf-starsexoplanetsradial-velocityvisible-astronomyProxima Centauri is the closest star to the Sun. This small, low-mass, mid M dwarf is known to host an Earth-mass exoplanet with an orbital period of 11.2 days within the habitable zone, as well as a long-period planet candidate with an orbital period of close to 5yr. We report on the analysis of a large set of observations taken with the ESPRESSO spectrograph at the aimed at a thorough evaluation of the presence of a third low-mass planetary companion, which started emerging during a previous campaign. Radial velocities (RVs) were calculated using both a cross-correlation function (CCF) and a template matching approach. The RV analysis includes a component to model Proxima`s activity using a Gaussian process (GP). We use the CCF's full width at half maximum to help constrain the GP, and we study other simultaneous observables as activity indicators in order to assess the nature of any potential RV signals. We detect a signal at 5.12+/-0.04 days with a semi-amplitude of 39+/-7cm/s. The analysis of subsets of the ESPRESSO data, the activity indicators, and chromatic RVs suggest that this signal is not caused by stellar variability but instead by a planetary companion with a minimum mass of 0.26+/-0.05M_{sun}_ (about twice the mass of Mars) orbiting at 0.029 au from the star. The orbital eccentricity is well constrained and compatible with a circular orbit.2022A&A...658A.115Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/658/A115CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/534/A133 : Proxima Cen chromospheric emission lines (Fuhrmeister+, 2011)J/A+A/603/A58 : Full spectrum of Proxima Centauri (Ribas+, 2017)J/AJ/153/93 : MOST photometry of Proxima (Kipping+, 2017)J/AJ/155/12 : Photometry of Proxima Centauri observed by BSST (Liu+, 2018)J/A+A/626/A111 : Proxima Cen flare activity temporal changes (Pavlenko+, 2019)J/AJ/157/226 : Proxima Centauri photometry from 2006 to 2017 (Feliz+, 2019)J/A+A/638/A120 : SPHERE maps around Proxima Cen (Gratton+, 2020)J/A+A/639/A77 : Proxima Cen RV, FWHM and fluxes (Suarez Mascareno+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/658/A115https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/658/A115http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/658/A115https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/658/A115https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/658/A115http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/658/A115GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/658/A115/tableProxima Cen ESPRESSO RV and FWHMrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian datedtime.epochdoubleRVRadial velocity from CCFm/sphys.veloc;pos.heliocentricdoublee_RVUncertainty on radial velocity from CCFm/sstat.errordoubleFWHMFull width at half maximum of the CCFm/sspect.line.widthdoublee_FWHMUncertainty on FWHM of the CCFm/sstat.error;phys.angSizedoubleRVTMRadial velocity from template-matching (TM)m/sphys.veloc;pos.heliocentricdoublee_RVTMUncertainty on radial velocity from TMm/sstat.errordoubleSubsetSubset of ESPRESSO data (ESP18, ESP19 or ESP21)meta.idchar