J/ApJS/264/12ivo://CDS.VizieR/J/ApJS/264/12doi:10.26093/cds/vizier.22640012CDSHan H.Wang S.Bai YuYang H.Fang X.Liu J.2024-08-13T20:15:04Z2023-04-17T08:17:43ZCDS support team

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

cds-question@unistra.frlate-type-starsline-intensitiesmetallicityvisible-astronomyspectroscopyphotometryBy using the LAMOST time-domain survey data, we study stellar activities based on the H{alpha} lines for about 2000 stars in four K2 plates. Two indices, R'_H{alpha}_ and R^+^_H{alpha}_, are computed from LAMOST spectra, the former of which is derived by excluding the photospheric contributions to the H{alpha} lines, while the latter is derived by further subtracting the non-dynamo-driven chromospheric emission. Meanwhile, the periodicity and variation amplitudes are computed from K2 light curves. Both the R'_H{alpha}_-Ro relation and R^+^_H{alpha}_-Ro relation show complicated profiles in the nonsaturated decay region. Hot stars show flatter slopes and a higher activity level than cool stars, and the behavior is more notable in the R^+^_H{alpha}_-Ro relation. This is consistent with recent studies using other activity proxies, including Lx/Lbol, R'_HK_, and amplitudes of optical light curves. This may suggest different kinds of stars follow different power laws in the decay region. Most of our targets have multiple observations, and some of them exhibit significant variability of H{alpha} emissions, which may cause the large scatters shown in the decay region. We find three targets exhibiting positive correlation in a rotational phase, possibly indicating that their optical light curves are dominated by hot faculae rather than cool starspots.2023ApJS..264...12Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/264/12CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/146 : LAMOST DR1 catalogs (Luo+, 2015)IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)V/156 : LAMOST DR7 catalogs (Luo+, 2019)J/A+A/397/147 : Activity-rotation relationship in stars (Pizzolato+ 2003)J/A+A/469/309 : Activity in late-type stars (Cincunegui+, 2007)J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)J/ApJ/743/48 : Stars with rot. periods & X-ray lum. (Wright+, 2011)J/ApJ/795/161 : Activity & rotation in Praesepe & Hyades (Douglas+, 2014)J/A+A/566/A43 : EPOCH Project. EROS-2 LMC periodic variables (Kim+, 2014)J/ApJ/851/116 : Long-term var. of Kepler sun-like stars (Montet+, 2017)J/ApJ/834/85 : H{alpha} emission in nearby M dwarfs (Newton+, 2017)J/MNRAS/485/3457 : Rotational modulation in TESS B stars (Balona+, 2019)J/A+A/628/A41 : KIC stars in Kepler/XMM-Newton (Pizzocaro+, 2019)J/ApJS/241/29 : Flare cat. through LC data of Kepler DR25 (Yang+, 2019)J/other/NatAs/4.03 : Rotation and activity across HR diagram (Lehtinen+, 2020)J/other/NatAs/4.658 : Rotation and activity across HR diagram (Lehtinen+, 2020)J/A+A/635/A43 : Stellar rot. periods from K2 (Reinhold+, 2020)J/ApJ/902/114 : Stellar X-ray activity. I. (Wang+, 2020)J/ApJS/246/9 : Stellar param. of LAMOST stars using SLAM (Zhang+, 2020)J/ApJS/247/9 : FGK stars activity in LAMOST-Kepler (Zhang+, 2020)J/ApJS/251/15 : LAMOST-Kepler/K2 survey (LK-MRS) 1st yr. (Zong+, 2020)J/other/RAA/21.292 : LAMOST Time-Domain survey, first results (Wang+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/264/12https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/264/12http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/264/12https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/264/12https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/264/12http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/264/12GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/264/12/param (All the quantities calculated from the Medium-Resolution data (Table 3) and Low-Resolution data (Table 4) together with stellar parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/264/12/param?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/264/12/param?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/264/12/param?GETtext/xml+votable180.050000true59.43187522.21213890.005555555555555556Cone search capability for table J/ApJS/264/12/ews (Medium-resolution (Table 1) and Low-resolution (Table 2) EWs of the H{alpha} lines)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/264/12/ews?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/264/12/ews?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/264/12/ews?GETtext/xml+votable180.050000true57.77562522.36822220.0055555555555555565/113 115-116 118-119 1063 1069 1074 1080 6002-6003 6006 6008-6009 6867 6870 6873 6875-6876 6878 6/367 378-379 451 457 468 470-471 484-485 496 4246-4247 4249 4251 4273 4275 4284-4285 4287 4290 4302 4324 4328-4330 23965 23967 24001-24004 24006-24007 24048 24050 27465 27467 27486 27489 27491 27497 27508 27510 27516https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/264/12?format=asciiOpticaldefaultJ/ApJS/264/12/paramAll the quantities calculated from the Medium-Resolution data (Table 3) and Low-Resolution data (Table 4) together with stellar parametersQMedium-Resolution (MRS) or Low-Resolution (LRS) datameta.code.qualcharLAMOSTLAMOST identifier (JHHMMSS.ss+DDMMSS.s)meta.id;meta.maincharNewNumber of equivalent widths measurements for this source (link to Tables 1+2)meta.numberintnullableEWHa[-6.7/1]? H{alpha} equivalent width, EW' (1)0.1nmspect.line.eqWidthfloatnullablee_EWHa[0/0.7]? Uncertainty in EWHa (1)0.1nmstat.errorfloatnullablelogRHa[-8.5/-3.2]? Log of RHa index, log (R'_H{alpha}_) (1)phys.luminosity;arith.ratiofloatnullablee_logRHa[4/7]? Uncertainty in logRHa (1)stat.errorfloatnullableDlogRHa[0/1.2]? Variability of logRHa (1)src.var.indexfloatnullableEWpHa[-7.7/0.3]? H{alpha} equivalent width, EW+ (2)0.1nmspect.line.eqWidthfloatnullablee_EWpHa[0/0.7]? Uncertainty in EWpHa (2)0.1nmstat.errorfloatnullablelogRpHa[-7/-3.2]? Log of RHa index, log (R^+^_H{alpha}_) (2)phys.luminosity;arith.ratiofloatnullablee_logRpHa[4/7]? Uncertainty in logRpHa (2)stat.errorfloatnullableDlogRpHa[0/0.7]? Variability of logRpHa (2)src.var.indexfloatnullableTeff[3366/8490] Effective temperatureKphys.temperature.effectivefloatlogg[3.5/4.9] Log surface gravitylog(cm.s**-2)phys.gravityfloat[Fe/H][-2.5/0.6] Metallicitylog(Sun)phys.abund.Zfloatlog(x)[-4.2/-3.9] Log of {chi} (3)phot.flux;arith.ratiofloattauC[2.7/139]? Convective turnover timedtime.scalefloatnullablePRot[0.29/30.58]? Rotational perioddtime.periodfloatnullableDR4+DR7Display the LAMOST -DR4 (V/153) and -DR7 (V/156) within 0.5"meta.ref.urlintnullableZ20Display data from LAMOST-K2 1st year (Zong+ 2020, J/ApJS/251/15)meta.ref.urlintnullableK2Display the K2 EPIC data (IV/34) within 3"meta.ref.urlchar_RAPositions from LAMOST names (right ascension part)degpos.eq.ra;meta.main_DEPositions from LAMOST names (declination part)degpos.eq.dec;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintm_LAMOST"2" if data in both MRS and LRS tables; "1" otherwisemeta.ref.urlintnullableSimbadSimbad column added by the CDSmeta.ref.urlcharJ/ApJS/264/12/ewsMedium-resolution (Table 1) and Low-resolution (Table 2) EWs of the H{alpha} linesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintQMedium-Resolution (MRS) or Low-Resolution (LRS) datameta.code.qualcharLAMOSTLAMOST identifier (JHHMMSS.ss+DDMMSS.s)meta.id;meta.maincharParamDisplay all the parameters for this source (Tables 3+4)meta.ref.urlintnullableEW[-180/21936]? Equivalent width; Angstroms0.1nmspect.line.eqWidthdoublenullablee_EW[0/250977]? Uncertainty in EW0.1nmstat.error;spect.line.eqWidthdoublenullableBMJD[58784.6/58950.6] Barycentric Modified Julian Datedtime.epochdoubleindexed_RAPositions from LAMOST names (right ascension part)degpos.eq.ra;meta.mainindexed_DEPositions from LAMOST names (declination part)degpos.eq.dec;meta.mainindexed