J/MNRAS/495/2949ivo://CDS.VizieR/J/MNRAS/495/2949doi:10.26093/cds/vizier.74952949CDSFang X.-S.Moni Bidin C.Zhao G.Zhang L.-Y.Bharat Kumar Y.2024-09-02T20:15:55Z2023-09-07T14:58:59ZCDS support team

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

cds-question@unistra.frlate-type-starsopen-star-clustersline-intensitiesastrometryeffective-temperaturevisible-astronomyspectroscopyWe present the results from a systematic study of temporal variation of stellar activity in young late-type stars. We used multi-epoch LAMOST (Large sky Area Multi-Object fiber Spectroscopic Telescope) low-resolution spectra of over 300 member candidates in three young open clusters: Pleiades, Praesepe, and Hyades. The spectral measurements of TiO band strength near 7050{AA} (TiO2) and equivalent width of H{alpha} line (EW_H{alpha}_) are used as the tracers of cool spot coverage and chromospheric emission strength, respectively. The analysis of time-variation patterns of these two tracers suggested that there exist detectable variabilities in TiO2 and EW_H{alpha}_, and their time-scales are in the wide range from days to years. Results showed that more active stars, younger and fast rotators, tend to have larger activity variations. There is a tendency of anticorrelation between temporal variations in TiO2 and EW_H{alpha}_. Also, appreciable anticorrelation in the rotational phase between H{alpha} emission and K2 brightness is detected in some M dwarfs, indicating spatial co-location of the plages with cool star-spots; however, cool stars do not always show such co-location features. Furthermore, spot coverage and H{alpha} emission were evident at all rotational phases of several M dwarfs, indicating a basal level of activity, perhaps due to many small and randomly located active regions in the atmosphere.2020MNRAS.495.2949Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/495/2949CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)V/164 : LAMOST DR5 catalogs (Luo+, 2019)J/ApJS/172/663 : Infrared observations of the Pleiades (Stauffer+, 2007)J/A+A/577/A148 : The Seven Sisters DANCe. I. Pleiades (Bouy+, 2015)J/ApJ/795/161 : Activity and rotation in Praesepe and the Hyadeshttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/495/2949https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/495/2949http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/495/2949https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/495/2949https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/495/2949http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/495/2949GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/495/2949/table3 (Basic information of stars and their statistics of measurements)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/495/2949/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/495/2949/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/495/2949/table3?GETtext/xml+votable180.050000true54.5974119423.108111940.0055555555555555565/113 115-116 118 1171 1174 1180 6/324-325 327 336 340 345 348-349 355 377-378 407 456-457 470 476 481 484-485 496-497 499 511 924 989 1026 1031 1041 1046 1158 1180 1199 1554 1564 4335 4689-4691 4694-4695 4700 4702 4709 4711 4716 4728-4729 4732 4896 23256 23370 23399 23531-23532 23534-23535 23545 23549 23551 24298 24336 24344https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/495/2949?format=asciiOpticaldefaultJ/MNRAS/495/2949/table2Measurements from the multi-epoch LAMOST spectra of representative samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordinte_EWHaError on EWHa0.1nmstat.errorfloatEWHb? Equivalent width of the H{beta} line0.1nmspect.line.eqWidthdoublenullablee_EWHb? Error on EWHb0.1nmstat.errordoublenullableTiO2n? Strength of TiO2n (1)spect.indexdoublenullablee_TiO2n? Error on TiO2nstat.errordoublenullableTiO5n? Strength of TiO5n (1)spect.indexdoublenullablee_TiO5n? Error on TiO5nstat.errordoublenullableClusterCluster namemeta.id.parentcharID[1/312] Internal identifiermeta.id;meta.mainintObsIDLAMOST spectrum identifiermeta.idlongBJDBarycentric Julian Date BJD-2450000.0dtime.epochdoubleEWHaEquivalent width of the H{alpha} line0.1nmspect.line.eqWidthfloatJ/MNRAS/495/2949/table3Basic information of stars and their statistics of measurementsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[1/312] Internal identifiermeta.id;meta.mainintGaiaDR2? Gaia DR2 source identifiermeta.idnullableRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainSimbadNameSimbad column added by the CDSmeta.idcharnullableCxy? Cross-correlation between TiO2n and EW_H{alpha}_stat.correlationfloatnullableClusterCluster namemeta.id.parentcharTeffEffective temperatureKphys.temperature.effectivefloatPeriod? Rotation perioddtime.perioddoublenullablemuEWHaMean value of the H{alpha} equivalent width0.1nmspect.line.eqWidth;stat.meanfloatAEWHaAmplitude of the H{alpha} equivalent width (maximum-minimum value)0.1nmspect.line.eqWidthfloatmuTiO2n? Mean value of the TiO2n strengthspect.indexdoublenullableATiO2n? Amplitude of the TiO2n strength (maximum-minimum value)spect.indexdoublenullable