J/A+A/689/A262ivo://CDS.VizieR/J/A+A/689/A262doi:10.26093/cds/vizier.36890262CDSTuomi M.Lehtinen J.J.Henry G.W.Hackman T.2025-02-24T20:01:01Z2024-09-20T09:45:51ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frvariable-starsvisible-astronomybroad-band-photometryStellar spot distribution has consequences on the observable periodic signals in long-time baseline ground-based photometry. We model the statistics of the dominating spots of two young and active Solar-type stars, V889 Her and LQ Hya, in order to obtain information on the underlying spot distribution, rotation of the star, as well as the orientation of the stellar axis of spin. By calculating estimates for spot-induced periodicities in independent subsets of photometric data, we obtain statistics based on the dominating spots in each subset, giving rise to largest-spot statistics accounting for stellar geometry and rotation, including differential rotation. Our simple statistical models are able to reproduce the observed distribution of photometric signals rather well. This also enables us to estimate the dependence of angular velocity of the spots as a function of latitude. Our results indicate that V889 Her has a non-monotonic differential rotation curve with a maximum angular velocity between latitudes of 37-40 deg and lower angular velocity at the pole than the equator. Our results for LQ Hya indicate that the star rotates much like a rigid body. Furthermore, the results imply that the monotonic Solar differential rotation curve may not be a universal model for other solar-type stars. The non-monotonicity of the differential rotation of V889 Her is commonly produced in magnetohydrodynamic simulations, which indicates that our results are realistic from a theoretical perspective.2024A&A...689A.262Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/689/A262CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/276/345 : Photometry of variable LQ Hya (Jestu 1993)J/A+A/394/505 : UBV photometry of LQ Hya (Berdyugina+, 2002)J/A+A/542/A38 : LQ Hya V-band differential light curve (Lehtinen+, 2012)J/A+A/575/A57 : LQ Hya activity and Li variations (Flores Soriano+, 2015)J/A+A/577/A120 : Carrier fit analysis of LQ Hya photometry (Olspert+, 2015)J/A+A/660/A141 : Light curve of the active star LQ Hya (Lehtinen+, 2022)J/A+A/622/A170 : V-band differential photometry for V889 Her (Willamo+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/689/A262https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/689/A262http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/689/A262https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/689/A262https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/689/A262http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/689/A262GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/689/A262/lqhyabLQ Hya B-band light curvedmagDifferential band Johnson (B or V) photometrymagphot.mag;arith.difffloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDReduced Heliocentric Julian Date (HJD-2400000)dtime.epochdoubleBand[BV] Observed bandinstr.bandpasscharJ/A+A/689/A262/lqhyavLQ Hya V-band light curverecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDReduced Heliocentric Julian Date (HJD-2400000)dtime.epochdoubledmagDifferential band Johnson (B or V) photometrymagphot.mag;arith.difffloatBand[BV] Observed bandinstr.bandpasscharJ/A+A/689/A262/v889herbV889 Her B-band light curverecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDReduced Heliocentric Julian Date (HJD-2400000)dtime.epochdoubledmagDifferential band Johnson (B or V) photometrymagphot.mag;arith.difffloatBand[BV] Observed bandinstr.bandpasscharJ/A+A/689/A262/v889hervV889 Her V-band light curverecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDReduced Heliocentric Julian Date (HJD-2400000)dtime.epochdoubledmagDifferential band Johnson (B or V) photometrymagphot.mag;arith.difffloatBand[BV] Observed bandinstr.bandpasschar