Time evolution and rotation of starspots on CoRoT-2 from the modelling of transit photometry

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dc.contributor.authorSilva-Valio A.
dc.contributor.authorLanza A.F.
dc.date.accessioned2024-03-13T01:11:30Z
dc.date.available2024-03-13T01:11:30Z
dc.date.issued2011
dc.description.abstractContext.CoRoT-2, the second planet-hosting star discovered by the CoRoT satellite, is a young and active star. A total of 77 transits were observed for this system over a period of 135 days. Aims.Small modulations detected in the optical light curve of the planetary transits are used to study the position, size, intensity, and temporal evolution of the photospheric spots on the surface of the star that are occulted by the planetary disk. Methods.We apply a spot model to these variations and create a spot map of the stellar surface of CoRoT-2 within the transit band for every transit. From these maps, we estimate the stellar rotation period and obtain the longitudes of the spots in a reference frame rotating with the star. Moreover, the spots temporal evolution is determined. This model achieves a spatial resolution of 2°. Results.Mapping of 392 spots vs. longitude indicates the presence of a region free of spots, close to the equator, which is reminiscent of the coronal holes observed on the Sun during periods of maximum activity. With this interpretation, the stellar rotation period within the transit latitudes of â̂'14.°6±10° is obtained from the auto-correlation function of the time-integrated spot flux deficit, which yields a rotation period of 4.48 days. With this period, the temporal evolution of the spot surface coverage in individual 20° longitude bins has periodicities ranging from 9 to 53 days with an average value of 31 ± 15 days. On the other hand, the longitude integrated spot flux, which is independent of the stellar rotation period, oscillates with a periodicity of 17.7 days, and its false-alarm probability is ∼ 3%. Conclusions.The rotation period of 4.48 days obtained here is shorter than the 4.54 days derived from the out-of-transit light modulation. Because the transit data sample a region close to the stellar equator while the period determined from out-of-transit data reflects the average rotation of the star, this is taken as an indication of a latitudinal differential rotation of about 3% or 0.042 rad/d. © 2011 ESO.
dc.description.volume529
dc.identifier.doi10.1051/0004-6361/201015382
dc.identifier.issn0004-6361
dc.identifier.urihttps://dspace.mackenzie.br/handle/10899/37000
dc.relation.ispartofAstronomy and Astrophysics
dc.rightsAcesso Aberto
dc.subject.otherlanguageplanetary systems
dc.subject.otherlanguagestars: activity
dc.subject.otherlanguagestars: individual: CoRoT-2
dc.subject.otherlanguagestarspots
dc.titleTime evolution and rotation of starspots on CoRoT-2 from the modelling of transit photometry
dc.typeArtigo
local.scopus.citations61
local.scopus.eid2-s2.0-79953198579
local.scopus.subjectA-spots
local.scopus.subjectAutocorrelation functions
local.scopus.subjectAverage values
local.scopus.subjectCoronal hole
local.scopus.subjectData sample
local.scopus.subjectDifferential rotation
local.scopus.subjectOptical light
local.scopus.subjectPlanetary system
local.scopus.subjectReference frame
local.scopus.subjectRotation period
local.scopus.subjectSpatial resolution
local.scopus.subjectSpot surface
local.scopus.subjectstars: activity
local.scopus.subjectstars: individual: CoRoT-2
local.scopus.subjectStarspots
local.scopus.subjectStellar rotation
local.scopus.subjectStellar surfaces
local.scopus.subjectTemporal evolution
local.scopus.subjectTime evolutions
local.scopus.subjectTransit photometry
local.scopus.updated2024-05-01
local.scopus.urlhttps://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=79953198579&origin=inward
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