J/AJ/138/1310ivo://CDS.VizieR/J/AJ/138/1310doi:10.26093/cds/vizier.51381310CDSNemec J.M.Walker A.Jeon Y.-B2017-06-26T11:50:41Z2012-02-13T09:39:58ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsglobular-star-clustersvariable-starsvisible-astronomybroad-band-photometryThe variable stars in the Large Magellanic Cloud star cluster NGC 2257 are reinvestigated using photometry (to ~20th mag) of over 400 new B, V CCD images taken with the CTIO 0.9m telescope on 14 nights in 2007 December and 2008 January. New period searches have been made using two independent algorithms (CLEAN, Period04); the resultant periods of most of the stars are consistent with the pulsation periods derived previously, and where there are discrepancies these have been resolved. For the B and V light curves, accurate Fourier coefficients and parameters are given. Six new variable stars have been discovered (V45-50), including a bright candidate long-period variable star showing secondary oscillations (V45) and two anomalously bright RRc stars (V48 and V50), which are shown to be brightened and reddened by nearby red giant stars. Also discovered among the previously known variable stars are three double-mode RR Lyrae stars (V8, V16, and V34) and several Blazhko variables. Archival Hubble Space Telescope images and the photometry by Johnson et al. (Cat. J/ApJ/527/199) have been used to define better the properties of the most crowded variable stars. The total number of cluster variable stars now stands at forty-seven: 23 RRab stars, four of which show Blazhko amplitude variations; 20 RRc stars, one showing clear Blazhko variations and another showing possible Blazhko variations; the three RRd stars, all having the dominant period ~0.36 day and period ratios P1/P0 ~0.7450; and an LPV star located near the tip of the red giant branch. A comparison of the RRd stars with those in other environments shows them to be most similar to those in IC4499.2009AJ....138.1310Nhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/138/1310CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/717/277 : Chemical composition of old LMC clusters (Mucciarelli+, 2010)J/ApJ/527/199 : HST observations of old clusters in the LMC (Johnson+, 1999)J/AJ/98/2086 : CCD photometry of NGC 2257 RR Lyrae (Walker 1989)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/138/1310https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/138/1310http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/138/1310https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/138/1310https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/138/1310http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/138/1310GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/138/1310/table2 (Cross-identifications, radial distances, and J2000.0 coordinates)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/138/1310/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/138/1310/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/138/1310/table2?GETtext/xml+votable180.050000true97.565375-64.31311110.0055555555555555566/37550 37551 389163.322582951404819e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/138/1310?format=asciiOpticaldefaultJ/AJ/138/1310/table2Cross-identifications, radial distances, and J2000.0 coordinatesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintr_NameStar source (1)meta.ref;pos.framecharNameCommon star name from previous investigationmeta.id;meta.maincharID[1/2170] Internal identification numbermeta.id;meta.mainintprimaryPSimbad column added by the CDSmeta.ref.urlcharrProjected distance from cluster centerarcsecpos.angDistanceintXpixX pixel coordinate from Dec. 2007 frame V7075pixpos.cartesian.xfloatYpixY pixel coordinate from Dec. 2007 frame V7075pixpos.cartesian.yfloatRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainJ/AJ/138/1310/table3Magnitude-averaged mean magnitudes and colorsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[1/2170] Internal identification numbermeta.id;meta.mainintXpixX pixel coordinate from Dec. 2007 frame V7075pixpos.cartesian.xdoubleYpixY pixel coordinate from Dec. 2007 frame V7075pixpos.cartesian.ydoubleVmagThe V band magnitudemagphot.mag;em.opt.Vfloate_VmagUncertainty in Vmagmagstat.error;phot.mag;em.opt.VfloatB-VThe (B-V) color indexmagphot.color;em.opt.B;em.opt.Vfloate_B-VUncertainty in B-Vmagstat.error;phot.color;em.opt.BfloatJ/AJ/138/1310/table4Sample photometry file (for V1=#409)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDHeliocentric Julian Datedtime.epochdoubleXpixX pixel coordinatepixpos.cartesian.xfloatYpixY pixel coordinatepixpos.cartesian.yfloatVmagCalibrated V band magnitudemagphot.mag;em.opt.Vfloate_VmagError in Vmagmagstat.error;phot.mag;em.opt.VfloatSeqIdentification number in framemeta.id;meta.mainintFrameThe frame label (1)meta.id;pos.frame;obs.fieldchar