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hal.structure.identifierInstitut de recherche en astrophysique et planétologie [IRAP]
dc.contributor.authorMATHIAS, P.
dc.contributor.authorAURIERE, M.
dc.contributor.authorARISTE, A. López
dc.contributor.authorPETIT, P.
dc.contributor.authorTESSORE, B.
hal.structure.identifierLaboratoire Univers et Particules de Montpellier [LUPM]
dc.contributor.authorJOSSELIN, E.
hal.structure.identifierLaboratoire Univers et Particules de Montpellier [LUPM]
dc.contributor.authorLÈBRE, A.
hal.structure.identifierLaboratoire Univers et Particules de Montpellier [LUPM]
dc.contributor.authorMORIN, J.
dc.contributor.authorWADE, G.
hal.structure.identifierFORMATION STELLAIRE 2018
dc.contributor.authorHERPIN, Fabrice
hal.structure.identifierJoseph Louis LAGRANGE [LAGRANGE]
dc.contributor.authorCHIAVASSA, A.
dc.contributor.authorMONTARGÈS, M.
hal.structure.identifierСофийски университет = Sofia University
dc.contributor.authorKONSTANTINOVA-ANTOVA, R.
hal.structure.identifierLaboratoire d'études spatiales et d'instrumentation en astrophysique [LESIA (UMR_8109)]
dc.contributor.authorKERVELLA, P.
hal.structure.identifierLaboratoire d'études spatiales et d'instrumentation en astrophysique [LESIA (UMR_8109)]
dc.contributor.authorPERRIN, G.
hal.structure.identifierInstitut de recherche en astrophysique et planétologie [IRAP]
dc.contributor.authorDONATI, J. -F.
dc.contributor.authorGRUNHUT, J.
dc.date.issued2018
dc.identifier.issn0004-6361
dc.description.abstractEnContext. Betelgeuse is an M-type supergiant that presents a circularly polarized (Stokes V) signal in its line profiles, interpreted in terms of a surface magnetic field.Aims. The weak circular polarization signal has been monitored over 7.5 years in order to follow its evolution on different timescales, and eventually to determine its physical origin. Linear polarization measurements have also been obtained regularly in the last few years.Methods. We used both the ESPaDOnS and Narval spectropolarimeters to obtain high signal-to-noise ratio spectra, which were processed by means of the least-squares deconvolution method. In order to ensure the reality of the very weak circular polarization, special care has been taken to limit instrumental effects. In addition, several tests were performed on the Stokes V signal to establish its stellar and Zeeman origin.Results. We confirm the magnetic nature of the circular polarization, pointing to a surface magnetic field of the order of 1 G. The Stokes V profiles present variations over different timescales, the most prominent one being close to the long secondary period (LSP; around 2000 d for Betelgeuse) often invoked in red evolved stars. This long period is also dominant for all the other Stokes parameters. The circular polarization is tentatively modeled by means of magnetic field concentrations mimicking spots, showing in particular that the velocity associated with each “spot” also follows the long timescale, and that this signal is nearly always slightly redshifted.Conclusions. From the coupled variations of both linear and circular polarization signatures in amplitude, velocity and timescale, we favour giant convection cells as the main engine at the origin of polarization signatures and variations in all the Stokes parameters. This strengthens support for the hypothesis that large convective cells are at the origin of the LSP.
dc.language.isoen
dc.publisherEDP Sciences
dc.subject.enstars: magnetic field
dc.subject.enstars: individual: Betelgeuse
dc.subject.enstars: late-type
dc.subject.ensupergiants
dc.title.enEvolution of the magnetic field of Betelgeuse from 2009–2017
dc.typeArticle de revue
dc.identifier.doi10.1051/0004-6361/201732542
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Astrophysique galactique [astro-ph.GA]
dc.identifier.arxiv1804.01831
bordeaux.journalAstronomy and Astrophysics - A&A
bordeaux.pageA116
bordeaux.volume615
bordeaux.peerReviewedoui
hal.identifierhal-01760230
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-01760230v1
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