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.authorCollier Cameron A.
dc.contributor.authorComparato M.
dc.contributor.authorCutispoto G.
dc.contributor.authorDe Medeiros J.R.
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.accessioned2024-03-13T01:36:22Z
dc.date.available2024-03-13T01:36:22Z
dc.date.issued2009
dc.description.abstractContext. The space experiment CoRoT has recently detected transits by a hot Jupiter across the disc of an active G7V star (CoRoT-Exo-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 ∼ percent is estimated. Individual spots form within the active longitudes and show an angular velocity ∼ 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. © 2008 ESO.
dc.description.firstpage193
dc.description.issuenumber1
dc.description.lastpage200
dc.description.volume493
dc.identifier.doi10.1051/0004-6361:200810591
dc.identifier.issn0004-6361
dc.identifier.urihttps://dspace.mackenzie.br/handle/10899/37454
dc.relation.ispartofAstronomy and Astrophysics
dc.rightsAcesso Aberto
dc.subject.otherlanguagePlanetary systems
dc.subject.otherlanguageStars: activity
dc.subject.otherlanguageStars: individual: CoRoT-Exo-2a
dc.subject.otherlanguageStars: late-type
dc.subject.otherlanguageStars: magnetic fields
dc.subject.otherlanguageStars: rotation
dc.titleMagnetic activity in the photosphere of CoRoT-Exo-2a Active longitudes and short-term spot cycle in a young Sun-like star
dc.typeArtigo
local.scopus.citations135
local.scopus.eid2-s2.0-58149291591
local.scopus.subjectPlanetary systems
local.scopus.subjectStars: activity
local.scopus.subjectStars: individual: CoRoT-Exo-2a
local.scopus.subjectStars: magnetic fields
local.scopus.subjectStars: rotation
local.scopus.updated2024-05-01
local.scopus.urlhttps://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=58149291591&origin=inward
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