A search for variable stars in M4 with K2 LCs

A search for variable stars in M4 with K2 LCsJ/ApJS/244/12ivo://CDS.VizieR/J/ApJS/244/12doi:10.26093/cds/vizier.22440012CDSWallace J.J.Hartman J.D.Bakos G.A.Bhatti W.2020-11-02T10:11:34Z2020-03-16T08:37:10ZCDS support team

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

cds-question@unistra.frglobular-star-clustersvariable-starsvisible-astronomynarrow-band-photometryWe extract light curves for 4554 objects with 9<G<19 in the K2 superstamp observations of the globular cluster M4, including 3784 cluster members, and search for variability. Among cluster-member objects, we detect 66 variables, of which 52 are new discoveries. Among objects not belonging to the cluster, we detect 24 variables, of which 20 are new discoveries. We additionally discover 57 cluster-member suspected variables, 10 cluster-non-member suspected variables, and four variables with ambiguous cluster membership. Our light curves reach sub-millimagnitude precision for the cluster horizontal branch, permitting us to detect asteroseismic activity in six horizontal branch stars outside the instability strip and one inside the strip but with only ~1mmag amplitude variability. Nineteen additional stars along the red giant branch also have detected asteroseismic variability. Several eclipsing binaries are found in the cluster, including a 4.6 day detached eclipsing binary and an EW-class eclipsing binary, as well as an EW with uncertain cluster membership and three other candidate EWs. A 22 day detached eclipsing binary is also found outside the cluster. We identify a candidate X-ray binary that is a cluster member with quiescent and periodic ~20mmag optical variability. We also obtain high-precision light curves for 10 of the previously known RR Lyrae variables in the cluster and identify one as a candidate Blazhko variable with a Blazhko period in excess of 78d.2019ApJS..244...12Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/244/12CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/gcvs : General Catalogue of Variable Stars (Samus+, 2007-2017)VII/202 : Globular Clusters in the Milky Way (Harris, 1997)I/337 : Gaia DR1 (Gaia Collaboration, 2016)V/150 : Updated cat. of variable stars in globular clusters (Clement+ 2017)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/PAZh/22/847 : Identification and coordinates in M4 (Shokin+, 1996)J/AJ/145/43 : CASE. V. Three eclipsing binaries in M4 (Kaluzny+, 2013)J/PASP/126/521 : UBVRIJHK photometry of RR Lyrae in M4 (Stetson+, 2014)J/MNRAS/442/2381 : Variable stars in M4 primary field (Nascimbeni+, 2014)J/MNRAS/452/3561 : Kepler EB stars. K2 Campaign 0 (LaCourse+, 2015)J/ApJ/808/11 : RR Lyrae stars in M4. II. Spitzer/IRAC phot. (Neeley+, 2015)J/MNRAS/463/1780 : Exoplanet candidates in Praesepe (M 44) (Libralato+, 2016)J/MNRAS/463/1831 : M67 Kepler/K2 variable stars (Nardiello+, 2016)J/ApJS/222/14 : Planetary cand. from 1st yr K2 mission (Vanderburg+, 2016)http://arks.princeton.edu/ark:/88435/dsp01h415pd368 : the associated data tohttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/244/12https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/244/12http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/244/12https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/244/12https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/244/12http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/244/12GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/244/12/table2 (Results for variables from Clement+ (2001AJ....122.2587C ; see V/150) and Stetson+ (2014, J/PASP/126/521))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/244/12/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/244/12/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/244/12/table2?GETtext/xml+votable180.050000true245.8573333-26.43797220.005555555555555556Cone search capability for table J/ApJS/244/12/table3 (Newly discovered cluster variables)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/244/12/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/244/12/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/244/12/table3?GETtext/xml+votable180.050000true245.798-26.444750.005555555555555556Cone search capability for table J/ApJS/244/12/table4 (Newly discovered variables that are indeterminable blends)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/244/12/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/244/12/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/244/12/table4?GETtext/xml+votable180.050000true245.7755833-26.46272220.005555555555555556Cone search capability for table J/ApJS/244/12/table5 (Newly discovered variables that are not cluster members)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/244/12/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/244/12/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/244/12/table5?GETtext/xml+votable180.050000true245.74425-26.483250.005555555555555556Cone search capability for table J/ApJS/244/12/table1 (Stars examined)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/244/12/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/244/12/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/244/12/table1?GETtext/xml+votable180.050000true245.8573333-26.43797220.0055555555555555566/429551.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/244/12?format=asciiOpticaldefaultJ/ApJS/244/12/table2Results for variables from Clement+ (2001AJ....122.2587C ; see V/150) and Stetson+ (2014, J/PASP/126/521)SimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintn_ID[VSAM] Note on object (1)meta.notecharIDIdentifier (G1)meta.id;meta.maincharf_ID[ghijklmuv] Flag on ID (1)meta.codecharRAJ2000[16] Gaia DR2 Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[26] Gaia DR2 Degree of Declination (J2000)pos.eq.dec;meta.mainGmag[9.4/21] Gaia DR2 G-band magnitudemagphot.mag;em.opt.Vfloatu_Per[~] Uncertainty flag on Permeta.code.errorcharPer[0.04/34]? Period of the variabilitydtime.perioddoublenullablePer2[30]? Upper range of variability (only for Table 2)dtime.periodintnullablef_Per[apdebt] Flag on Per (1)meta.codechare_Per[0.03/8000]? Uncertainty of Per (see Section 2.8)0.0001dstat.errorfloatnullableu_Amp[~] Uncertainty flag on Ampmeta.code.errorcharAmp[-40/990]? Amplitude of the variability (see Section 2.8) (2)mmagsrc.varfloatnullablef_Amp[no] Flag on Amp (1)meta.codecharu_Epoch[~] Uncertainty flag on Epochmeta.code.error;time.epochcharEpoch? Epoch of the minimum of variability, expressed in KBJD (BJD-2454833) (3)dtime.epochfloatnullableTypeClassification based on the GCVS variability types (5)meta.code.class;src.classcharf_Type[qr] Flag on Type (1)meta.codechar

J/ApJS/244/12/table3Newly discovered cluster variablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintn_ID[VSAM] Note on object (1)meta.notecharIDIdentifier (G1)meta.id;meta.maincharf_ID[ghijklmuv] Flag on ID (1)meta.codecharRAJ2000[16] Gaia DR2 Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[26] Gaia DR2 Degree of Declination (J2000)pos.eq.dec;meta.mainGmag[9.4/21] Gaia DR2 G-band magnitudemagphot.mag;em.opt.Vfloatu_Per[~] Uncertainty flag on Permeta.code.errorcharPer[0.04/34]? Period of the variabilitydtime.perioddoublenullablef_Per[apdebt] Flag on Per (1)meta.codechare_Per[0.03/8000]? Uncertainty of Per (see Section 2.8)0.0001dstat.errorfloatnullableu_Amp[~] Uncertainty flag on Ampmeta.code.errorcharAmp[-40/990]? Amplitude of the variability (see Section 2.8) (2)mmagsrc.varfloatnullablef_Amp[no] Flag on Amp (1)meta.codecharu_Epoch[~] Uncertainty flag on Epochmeta.code.error;time.epochcharEpoch? Epoch of the minimum of variability, expressed in KBJD (BJD-2454833) (3)dtime.epochfloatnullableMethMethod (only for Tables 3 and 5) (4)meta.notecharTypeClassification based on the GCVS variability types (5)meta.code.class;src.classcharf_Type[qr] Flag on Type (1)meta.codechar

J/ApJS/244/12/table4Newly discovered variables that are indeterminable blendsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintn_ID[VSAM] Note on object (1)meta.notecharIDIdentifier (G1)meta.id;meta.maincharf_ID[ghijklmuv] Flag on ID (1)meta.codecharRAJ2000[16] Gaia DR2 Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[26] Gaia DR2 Degree of Declination (J2000)pos.eq.dec;meta.mainGmag[9.4/21] Gaia DR2 G-band magnitudemagphot.mag;em.opt.Vfloatu_Per[~] Uncertainty flag on Permeta.code.errorcharPer[0.04/34]? Period of the variabilitydtime.perioddoublenullablef_Per[apdebt] Flag on Per (1)meta.codechare_Per[0.03/8000]? Uncertainty of Per (see Section 2.8)0.0001dstat.errorfloatnullableu_Amp[~] Uncertainty flag on Ampmeta.code.errorcharAmp[-40/990]? Amplitude of the variability (see Section 2.8) (2)mmagsrc.varfloatnullablef_Amp[no] Flag on Amp (1)meta.codecharu_Epoch[~] Uncertainty flag on Epochmeta.code.error;time.epochcharEpoch? Epoch of the minimum of variability, expressed in KBJD (BJD-2454833) (3)dtime.epochfloatnullableTypeClassification based on the GCVS variability types (5)meta.code.class;src.classcharf_Type[qr] Flag on Type (1)meta.codecharMm[0/1]? Cluster membership probability from Table 1 (only for Tables 4 and 5)stat.probabilityfloatnullablef_Mm[fcs] Flag on Mm (1)meta.codechar

J/ApJS/244/12/table5Newly discovered variables that are not cluster membersf_Mm[fcs] Flag on Mm (1)meta.codecharf_Type[qr] Flag on Type (1)meta.codecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintn_ID[VSAM] Note on object (1)meta.notecharIDIdentifier (G1)meta.id;meta.maincharf_ID[ghijklmuv] Flag on ID (1)meta.codecharRAJ2000[16] Gaia DR2 Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[26] Gaia DR2 Degree of Declination (J2000)pos.eq.dec;meta.mainGmag[9.4/21] Gaia DR2 G-band magnitudemagphot.mag;em.opt.Vfloatu_Per[~] Uncertainty flag on Permeta.code.errorcharPer[0.04/34]? Period of the variabilitydtime.perioddoublenullablef_Per[apdebt] Flag on Per (1)meta.codechare_Per[0.03/8000]? Uncertainty of Per (see Section 2.8)0.0001dstat.errorfloatnullableu_Amp[~] Uncertainty flag on Ampmeta.code.errorcharAmp[-40/990]? Amplitude of the variability (see Section 2.8) (2)mmagsrc.varfloatnullablef_Amp[no] Flag on Amp (1)meta.codecharu_Epoch[~] Uncertainty flag on Epochmeta.code.error;time.epochcharEpoch? Epoch of the minimum of variability, expressed in KBJD (BJD-2454833) (3)dtime.epochfloatnullableMethMethod (only for Tables 3 and 5) (4)meta.notecharTypeClassification based on the GCVS variability types (5)meta.code.class;src.classcharMm[0/1]? Cluster membership probability from Table 1 (only for Tables 4 and 5)stat.probabilityfloatnullable

J/ApJS/244/12/table1Stars examinedDRGaia data realease (2)meta.softwarecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVarmeta.ref.urlcharIDIdentifier (G1)meta.id;meta.maincharprimaryGaiaGaia identifier within the release (2)meta.idRAJ2000[16] Hour of Right Ascension (J2000) (3)pos.eq.ra;meta.mainDEJ2000[26] Degree of Declination (J2000) (3)pos.eq.dec;meta.mainGmag[9.4/21] Gaia magnitude (4)magphot.mag;em.opt.VfloatGBPmag[9.7/20.5]? Gaia blue passband magnitude (4)magphot.mag;em.opt.BfloatnullableGRPmag[9/19.5]? Gaia red passband magnitude (4)magphot.mag;em.opt.RfloatnullableN[701/3773] Number of points in light curve (5)meta.numberintRMS[0.1/1261] Light curve RMS (6)mmagstat.stdev;phot.magfloatMm[0/1]? Membership probability as calculated by Wallace (2018RNAAS...2d.213W)stat.probability;meta.modelledfloatnullablen_MmNote when membership is null (7)meta.notecharFileDownload the CSV LC filemeta.ref.urlcharLCLC plotmeta.ref.urlchar