Magnetic activity in the photosphere of CoRoT-Exo-2a: Active longitudes and short-term spot cycle in a young Sun-like star

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dc.contributor.authorLanza, A. F.
dc.contributor.authorPagano, I.
dc.contributor.authorLeto, G.
dc.contributor.authorMessina, S.
dc.contributor.authorAigrain, S.
dc.contributor.authorAlonso, R.
dc.contributor.authorAuvergne, M.
dc.contributor.authorBaglin, A.
dc.contributor.authorBarge, P.
dc.contributor.authorBonomo, A. S.
dc.contributor.authorBoumier, P.
dc.contributor.authorCameron, A. Collier
dc.contributor.authorComparato, M.
dc.contributor.authorCutispoto, G.
dc.contributor.authorMedeiros, José Renan de
dc.contributor.authorFoing, B.
dc.contributor.authorKaiser, A.
dc.contributor.authorMoutou, C.
dc.contributor.authorParihar, P. S.
dc.contributor.authorSilva-Valio, A.
dc.contributor.authorWeiss, W. W.
dc.date.accessioned2020-05-18T18:30:06Z
dc.date.available2020-05-18T18:30:06Z
dc.date.issued2008
dc.description.resumoContext. The space experiment CoRoT has recently detected transits by a hot Jupiter across the disc of an active G7V star (CoRoTExo-2a) that can be considered as a good proxy for the Sun at an age of approximately 0.5 Gyr. Aims. We present a spot modelling of the optical variability of the star during 142 days of uninterrupted observations performed by CoRoT with unprecedented photometric precision. Methods. We apply spot modelling approaches previously tested in the case of the Sun by modelling total solar irradiance variations, a good proxy for the optical flux variations of the Sun as a star. The best results in terms of mapping of the surface brightness inhomogeneities are obtained by means of maximum entropy regularized models. To model the light curve of CoRoT-Exo-2a, we take into account the photometric effects of both cool spots and solar-like faculae, adopting solar analogy. Results. Two active longitudes initially on opposite hemispheres are found on the photosphere of CoRoT-Exo-2a with a rotation period of 4.522 ± 0.024 days. Their separation changes by ≈80◦ during the time span of the observations. From this variation, a relative amplitude of the surface differential rotation lower than ∼1 percent is estimated. Individual spots form within the active longitudes and show an angular velocity ∼1 percent lower than that of the longitude pattern. The total spotted area shows a cyclic oscillation with a period of 28.9 ± 4.3 days, which is close to 10 times the synodic period of the planet as seen by the rotating active longitudes. We discuss the effects of solar-like faculae on our models, finding indications of a facular contribution to the optical flux variations of CoRoT-Exo-2a being significantly smaller than in the present Sun. Conclusions. The implications of such results for the internal rotation of CoRoT-Exo-2a are discussed, based on solar analogy. A possible magnetic star-planet interaction is suggested by the cyclic variation of the spotted area. Alternatively, the 28.9-d cycle may be related to Rossby-type waves propagating in the subphotospheric layers of the star.pt_BR
dc.identifier.citationMEDEIROS, José Renan de et al. Magnetic activity in the photosphere of CoRoT-Exo-2a. Astronomy & Astrophysics (Berlin), v. 493, p. 193-200, 2009. ISSN 1432-0746 versão online. DOI https://doi.org/10.1051/0004-6361:200810591. Disponível em: https://www.aanda.org/articles/aa/abs/2009/01/aa10591-08/aa10591-08.html. Acesso em: 18 maio 2020. Reproduzido com permissão da Astronomy & Astrophysics, © ESO.pt_BR
dc.identifier.doihttps://doi.org/10.1051/0004-6361:200810591
dc.identifier.issn0004-6361 (print), 1432-0746 (online)
dc.identifier.urihttps://repositorio.ufrn.br/jspui/handle/123456789/28997
dc.languageenpt_BR
dc.publisherAstronomy & Astrophysicspt_BR
dc.subjectStars: magnetic fieldspt_BR
dc.subjectStars: late-typept_BR
dc.subjectStars: activitypt_BR
dc.subjectStars: rotationpt_BR
dc.subjectStars: individual: CoRoT-Exo-2apt_BR
dc.subjectPlanetary systemspt_BR
dc.titleMagnetic activity in the photosphere of CoRoT-Exo-2a: Active longitudes and short-term spot cycle in a young Sun-like starpt_BR
dc.typearticlept_BR

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