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dc.contributor.authorMaldonado, J.
dc.contributor.authorPhillips, D. F.
dc.contributor.authorDumusque, X.
dc.contributor.authorCollier Cameron, A.
dc.contributor.authorHaywood, R. D.
dc.contributor.authorLanza, A. F.
dc.contributor.authorMicela, G.
dc.contributor.authorMortier, A.
dc.contributor.authorSaar, S. H.
dc.contributor.authorSozzetti, A.
dc.contributor.authorRice, K.
dc.contributor.authorMilbourne, T.
dc.contributor.authorCecconi, M.
dc.contributor.authorCegla, H. M.
dc.contributor.authorCosentino, R.
dc.contributor.authorCostes, J.
dc.contributor.authorGhedina, A.
dc.contributor.authorGonzalez, M.
dc.contributor.authorGuerra, J.
dc.contributor.authorHernández, N.
dc.contributor.authorLi, C. -H.
dc.contributor.authorLodi, M.
dc.contributor.authorMalavolta, L.
dc.contributor.authorMolinari, E.
dc.contributor.authorPepe, F.
dc.contributor.authorPiotto, G.
dc.contributor.authorPoretti, E.
dc.contributor.authorSasselov, D.
dc.contributor.authorSan Juan, J.
dc.contributor.authorThompson, S.
dc.contributor.authorUdry, S.
dc.contributor.authorWatson, C.
dc.date.accessioned2019-07-22T15:30:01Z
dc.date.available2019-07-22T15:30:01Z
dc.date.issued2019-07-10
dc.identifier.citationMaldonado , J , Phillips , D F , Dumusque , X , Collier Cameron , A , Haywood , R D , Lanza , A F , Micela , G , Mortier , A , Saar , S H , Sozzetti , A , Rice , K , Milbourne , T , Cecconi , M , Cegla , H M , Cosentino , R , Costes , J , Ghedina , A , Gonzalez , M , Guerra , J , Hernández , N , Li , C -H , Lodi , M , Malavolta , L , Molinari , E , Pepe , F , Piotto , G , Poretti , E , Sasselov , D , San Juan , J , Thompson , S , Udry , S & Watson , C 2019 , ' Temporal evolution and correlations of optical activity indicators measured in Sun-as-a-star observations ' , Astronomy & Astrophysics , vol. 627 , A118 . https://doi.org/10.1051/0004-6361/201935233en
dc.identifier.issn0004-6361
dc.identifier.otherPURE: 260248603
dc.identifier.otherPURE UUID: 36603d86-2033-4b70-9ad6-292606efa1f4
dc.identifier.otherBibCode: 2019A&A...627A.118M
dc.identifier.otherORCID: /0000-0002-8863-7828/work/59953645
dc.identifier.otherWOS: 000474702300002
dc.identifier.otherScopus: 85069521475
dc.identifier.urihttps://hdl.handle.net/10023/18149
dc.descriptionA.C.C. acknowledges support from the Science and Technology Facilities Council (STFC) consolidated grant number ST/R000824/1.en
dc.description.abstractContext. Understanding stellar activity in solar-type stars is crucial for the physics of stellar atmospheres as well as for ongoing exoplanet programmes. Aims. We aim to test how well we understand stellar activity using our own star, the Sun, as a test case. Methods. We performed a detailed study of the main optical activity indicators (Ca II H & K, Balmer lines, Na I D1 D2, and He I D3) measured for the Sun using the data provided by the HARPS-N solar-telescope feed at the Telescopio Nazionale Galileo. We made use of periodogram analyses to study solar rotation, and we used the pool variance technique to study the temporal evolution of active regions. The correlations between the different activity indicators as well as the correlations between activity indexes and the derived parameters from the cross-correlation technique are analysed. We also study the temporal evolution of these correlations and their possible relationship with indicators of inhomogeneities in the solar photosphere like sunspot number or radio flux values. Results. The value of the solar rotation period is found in all the activity indicators, with the only exception being Hδ. The derived values vary from 26.29 days (Hγ line) to 31.23 days (He I). From an analysis of sliding periodograms we find that in most of the activity indicators the spectral power is split into several “bands” of periods around 26 and 30 days. They might be explained by the migration of active regions between the equator and a latitude of ∼30°, spot evolution, or a combination of both effects. A typical lifetime of active regions of approximately ten rotation periods is inferred from the pooled variance diagrams, which is in agreement with previous works. We find that Hα, Hβ, Hγ, Hϵ, and He I show a significant correlation with the S index. Significant correlations between the contrast, bisector span, and the heliocentric radial velocity with the activity indexes are also found. We show that the full width at half maximum, the bisector, and the disc-integrated magnetic field correlate with the radial velocity variations. The correlation of the S index and Hα changes with time, increasing with larger sun spot numbers and solar irradiance. A similar tendency with the S index and radial velocity correlation is also present in the data. Conclusions. Our results are consistent with a scenario in which higher activity favours the correlation between the S index and the Hα activity indicators and between the S index and radial velocity variations.
dc.format.extent17
dc.language.isoeng
dc.relation.ispartofAstronomy & Astrophysicsen
dc.rightsCopyright © ESO 2019. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1051/0004-6361/201935233en
dc.subjectSun: activityen
dc.subjectSun: chromosphereen
dc.subjectSun: rotationen
dc.subjectTechniques: spectroscopicen
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.subject3rd-NDASen
dc.subject.lccQBen
dc.subject.lccQCen
dc.titleTemporal evolution and correlations of optical activity indicators measured in Sun-as-a-star observationsen
dc.typeJournal articleen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.description.versionPostprinten
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.contributor.institutionUniversity of St Andrews. St Andrews Centre for Exoplanet Scienceen
dc.identifier.doihttps://doi.org/10.1051/0004-6361/201935233
dc.description.statusPeer revieweden
dc.identifier.urlhttp://adsabs.harvard.edu/abs/2019A%26A...627A.118Men
dc.identifier.grantnumberST/R00824/1en
dc.identifier.grantnumberST/R003203/1en


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