dc.contributor.author |
Lanza, A. F |
|
dc.contributor.author |
Pagano, I |
|
dc.contributor.author |
Leto, G |
|
dc.contributor.author |
Messina, S |
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dc.contributor.author |
Aigrain, S |
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dc.contributor.author |
Alonso, R |
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dc.contributor.author |
Auvergne, M |
|
dc.contributor.author |
Baglin, A |
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dc.contributor.author |
Barge, P |
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dc.contributor.author |
Bonomo, A. S |
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dc.contributor.author |
Boumier, P |
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dc.contributor.author |
Collier Cameron, A |
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dc.contributor.author |
Comparato, M |
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dc.contributor.author |
Cutispoto, G |
|
dc.contributor.author |
de Medeiros, J. R |
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dc.contributor.author |
Foing, B |
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dc.contributor.author |
Kaiser, A |
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dc.contributor.author |
Moutou, C |
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dc.contributor.author |
Parihar, P. S |
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dc.contributor.author |
Silva-Valio, A |
|
dc.contributor.author |
Weiss, W. W |
|
dc.date.accessioned |
2009-01-30T15:54:11Z |
|
dc.date.available |
2009-01-30T15:54:11Z |
|
dc.date.issued |
2009-01 |
|
dc.identifier.citation |
Astronomy and Astrophysics, Vol. 493, No. 1, pp. 193 - 200 |
en |
dc.identifier.issn |
0004-6361 |
|
dc.identifier.uri |
http://hdl.handle.net/2248/4308 |
|
dc.description.abstract |
Context: 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 ~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. |
en |
dc.language.iso |
en |
en |
dc.publisher |
EDP Sciences |
en |
dc.relation.uri |
http://arxiv.org/abs/0811.0461 |
en |
dc.relation.uri |
http://dx.doi.org/10.1051/0004-6361:200810591 |
en |
dc.rights |
© European Southern Observatory |
en |
dc.subject |
Stars: Magnetic Fields |
en |
dc.subject |
Stars: Late-Type |
en |
dc.subject |
Stars: Activity |
en |
dc.subject |
Stars: Rotation |
en |
dc.subject |
Stars: Individual: CoRoT-Exo-2a |
en |
dc.subject |
Planetary Systems |
en |
dc.title |
Magnetic activity in the photosphere of CoRoT-Exo-2a. Active longitudes and short-term spot cycle in a young Sun-like star |
en |
dc.type |
Article |
en |