J/AJ/117/2868ivo://CDS.VizieR/J/AJ/117/2868doi:10.26093/cds/vizier.51172868CDSLee J.-W.Carney B.W.2020-06-19T11:58:24Z2006-06-02T11:39:46ZCDS support team

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

cds-question@unistra.frvariable-starsccd-photometryvisible-astronomybroad-band-photometryWe present BV CCD photometry for 30 RR Lyrae variables, including 13 newly discovered, in the Oosterhoff type II globular cluster M2. New light curves and ephemerides are presented. Our observations cover magnitudes ranging from the red giant branch tip to ~3mag below the turnoff, allowing us to determine accurate fundamental photometric parameters. With the discovery of new RR Lyrae variables, the mean periods of the RRab and RRc variables are <P_ab_>=0.685+/-0.022days and <P_c_>=0.333+/-0.013days, respectively. The number ratio of the RRc type variables to the total number of RR Lyrae type variables is n(c)/n(ab+c)=0.40. The RR Lyrae pulsational mode transition occurs between the fundamental period of 0.528-days and 0.556-days. From star counts along the horizontal branch (HB), we obtain two HB color distribution indices, (B-R)/(B+V+R)=0.92 and B2/(B+V+R)=0.46. The period-change rates are also derived. The mean period-change rate from six RRab variables is <{beta}>=0.06+/-0.04days/Myr, which agrees well with the predictions of Lee's 1991 model. Our color-magnitude diagram shows a very extended blue HB tail, and there are no significant blue HB gaps in M2.1999AJ....117.2868Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/117/2868CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/97 : Updated 3rd Cat Variable Stars in Globular Clusters (Clement+ 1997)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/117/2868https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/117/2868http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/117/2868https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/117/2868https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/117/2868http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/117/2868GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/117/2868/table2 (Color-magnitude diagram data)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/117/2868/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/117/2868/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/117/2868/table2?GETtext/xml+votable180.050000true323.46935667-0.860953610.005555555555555556Cone search capability for table J/AJ/117/2868/table3 (Parameters for M2 RR Lyrae variables)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/117/2868/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/117/2868/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/117/2868/table3?GETtext/xml+votable180.050000true323.3487467-0.80128440.0055555555555555566/19090 190913.322582951404819e-19 4.920466254354166e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/117/2868?format=asciiOpticaldefaultJ/AJ/117/2868/table2Color-magnitude diagram datarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLCIdentification number (Cl* NGC 7089 LC NNNNN in Simbad)meta.idintXposX position (1)pixpos.cartesian.x;instr.detdoubleYposY position (1)pixpos.cartesian.y;instr.detdoubleB-VB-V colour indexmagphot.color;em.opt.B;em.opt.VfloatVmagV magnitudemagphot.mag;em.opt.Vfloat_RAPosition computed from a comparison with UCAC2 catalog I/289 ({sigma}=50mas) (right ascension part)degpos.eq.ra;meta.mainindexed_DEPosition computed from a comparison with UCAC2 catalog I/289 ({sigma}=50mas) (declination part)degpos.eq.dec;meta.mainindexedJ/AJ/117/2868/table3Parameters for M2 RR Lyrae variablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameRR Lyrae name (G1)meta.id;meta.maincharprimaryPerPerioddtime.perioddoubleEp0Epoch at {phi}=0.00dtime.epochdoubleAVAbsorption in V bandmagphot.mag;em.opt.VfloatABAbsorption in B bandmagphot.mag;em.opt.Bfloat<Vmag>Magnitude-weighted integrated V magnitudemagphot.mag;em.opt.Vfloat<Bmag>Magnitude-weighted integrated B magnitudemagphot.mag;em.opt.Bfloat<Vint>Intensity-weighted integrated V magnitudemagphot.mag;em.opt.Vfloat<Bint>Intensity-weighted integrated B magnitudemagphot.mag;em.opt.BfloatClass[ab c] RR Lyrae classmeta.code.classcharSimbadNameSimbad column added by the CDSmeta.idchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.mainnullable_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainnullableJ/AJ/117/2868/table4RR Lyrae datarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameRR Lyrae name (G1)meta.id;meta.maincharHJDHeliocentric Julian datedtime.epochdoublePhase[0/1] Phasetime.phasefloatVmagV magnitudemagphot.mag;em.opt.VfloatB-VB-V colour indexmagphot.color;em.opt.B;em.opt.VfloatBmagB magnitudemagphot.mag;em.opt.Bfloat