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dc.contributor.authorDonati, J.-F.
dc.contributor.authorHébrard, E.
dc.contributor.authorHussain, G.
dc.contributor.authorMoutou, C.
dc.contributor.authorGrankin, K.
dc.contributor.authorBoisse, I.
dc.contributor.authorMorin, J.
dc.contributor.authorGregory, S. G.
dc.contributor.authorVidotto, A. A.
dc.contributor.authorBouvier, J.
dc.contributor.authorAlencar, S. H. P.
dc.contributor.authorDelfosse, X.
dc.contributor.authorDoyon, R.
dc.contributor.authorTakami, M.
dc.contributor.authorJardine, M. M.
dc.contributor.authorFares, R.
dc.contributor.authorCameron, A. C.
dc.contributor.authorMénard, F.
dc.contributor.authorDougados, C.
dc.contributor.authorHerczeg, G.
dc.identifier.citationDonati , J-F , Hébrard , E , Hussain , G , Moutou , C , Grankin , K , Boisse , I , Morin , J , Gregory , S G , Vidotto , A A , Bouvier , J , Alencar , S H P , Delfosse , X , Doyon , R , Takami , M , Jardine , M M , Fares , R , Cameron , A C , Ménard , F , Dougados , C & Herczeg , G 2014 , ' Modelling the magnetic activity and filtering radial velocity curves of young Suns : the weak-line T Tauri star LkCa 4 ' , Monthly Notices of the Royal Astronomical Society , vol. 444 , no. 4 , pp. 3220-3229 .
dc.identifier.otherBibCode: 2014MNRAS.444.3220D
dc.identifier.otherORCID: /0000-0002-8863-7828/work/58531447
dc.identifier.otherORCID: /0000-0002-1466-5236/work/57821872
dc.descriptionSGG acknowledges support from the Science & Technology Facilities Council (STFC) via an Ernest Rutherford Fellowship [ST/J003255/1]. SHPA acknowledges financial support from CNPq, CAPES and Fapemig.en
dc.description.abstractWe report results of a spectropolarimetric and photometric monitoring of the weak-line T Tauri star LkCa 4 within the Magnetic Topologies of Young Stars and the Survival of close-in giant Exoplanets (MaTYSSE) programme, involving ESPaDOnS at the Canada–France–Hawaii Telescope. Despite an age of only 2 Myr and a similarity with prototypical classical T Tauri stars, LkCa 4 shows no evidence for accretion and probes an interesting transition stage for star and planet formation. Large profile distortions and Zeeman signatures are detected in the unpolarized and circularly polarized lines of LkCa 4 using Least-Squares Deconvolution (LSD), indicating the presence of brightness inhomogeneities and magnetic fields at the surface of LkCa 4. Using tomographic imaging, we reconstruct brightness and magnetic maps of LkCa 4 from sets of unpolarized and circularly polarized LSD profiles. The large-scale field is strong and mainly axisymmetric, featuring a ≃2 kG poloidal component and a ≃1 kG toroidal component encircling the star at equatorial latitudes – the latter making LkCa 4 markedly different from classical T Tauri stars of similar mass and age. The brightness map includes a dark spot overlapping the magnetic pole and a bright region at mid-latitudes – providing a good match to the contemporaneous photometry. We also find that differential rotation at the surface of LkCa 4 is small, typically ≃5.5 times weaker than that of the Sun, and compatible with solid-body rotation. Using our tomographic modelling, we are able to filter out the activity jitter in the radial velocity curve of LkCa 4 (of full amplitude 4.3 km s−1) down to an rms precision of 0.055 km s−1. Looking for hot Jupiters around young Sun-like stars thus appears feasible, even though we find no evidence for such planets around LkCa 4.
dc.relation.ispartofMonthly Notices of the Royal Astronomical Societyen
dc.subjectTechniques: polarimetricen
dc.subjectStars: formationen
dc.subjectStars: imagingen
dc.subjectStars: individual: LkCa 4en
dc.subjectStars: magnetic fielden
dc.subjectStars: rotationen
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.titleModelling the magnetic activity and filtering radial velocity curves of young Suns : the weak-line T Tauri star LkCa 4en
dc.typeJournal articleen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.contributor.sponsorPPARC - Now STFCen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.description.statusPeer revieweden

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