J/MNRAS/461/1032ivo://CDS.VizieR/J/MNRAS/461/1032doi:10.26093/cds/vizier.74611032CDSArellano Ferro A.Ahumada J.A.Kains N.Luna A.2024-08-16T20:17:41Z2016-12-12T13:15:22ZCDS support team

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

cds-question@unistra.frvariable-starsSecular period variations, {beta}=dP/dt, in 76 RR Lyrae stars in the globular cluster M5 are analysed using our most recent CCD V photometry and the historical photometric data base available in the literature since 1889. This provides a time baseline of up to 118 yr for these variables. The analysis was performed using two independent approaches: first, the classical O-C behaviour of the time of maximum light, and second, via a grid (P, {beta}), where the solution producing the minimum scatter in the phased light curve is chosen. The results of the two methods agree satisfactorily. This allowed a new interpretation of the nature of the period changes in many RR Lyrae stars in M5. It is found that in 96 per cent of the stars studied no irregular or stochastic variations need to be claimed, but that 66 per cent of the population shows steady period increases or decreases, and that 34 per cent of the periods seem to have been stable over the last century. The lack of systematic positive or negative period variations in RR Lyrae stars in other globular clusters is addressed, and the paradigm of period changes being a consequence of stellar evolution is discussed in terms of chemical variations near the stellar core and of multiple stellar populations. In M5 we found a small positive average value of {beta} and a small surplus of RRab stars with a period increase. Nevertheless, in M5 we have been able to isolate a group of likely evolved stars that systematically show positive, and in some cases large, period change rates.2016MNRAS.461.1032Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/461/1032CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/411/1744 : Observations of RR Lyr stars in M5 (Szeidl+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/461/1032https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/461/1032http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/461/1032https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/461/1032https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/461/1032http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/461/1032GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/461/1032/table3 (New periods and period change rates for RR Lyrae stars in M5)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/461/1032/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/461/1032/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/461/1032/table3?GETtext/xml+votable180.050000true229.6477352.12483890.005555555555555556Cone search capability for table J/MNRAS/461/1032/table2a (Fundamental periods of studied stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/461/1032/table2a?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/461/1032/table2a?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/461/1032/table2a?GETtext/xml+votable180.050000true229.6477352.12483890.0055555555555555566/31416-31417https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/461/1032?format=asciidefaultJ/MNRAS/461/1032/table3New periods and period change rates for RR Lyrae stars in M5recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintplotShow the O-C diagramsmeta.ref.urlcharVNameVariable namemeta.id;meta.maincharVTypeVarialbe typesrc.classcharP0Period at E0 from Arellano Ferro et al. (2016, Cat. J/other/ApSS/351.175)dtime.perioddoubleE0Epoch (HJD-2450000)dtime.epochdoubleE0+A0? Corrected epoch (HJD-2450000)dtime.epochdoublenullableP0+A1? Corrected perioddtime.perioddoublenullablebeta0(O-C)? Period change rate, dP/dt, from (O-C)d/Myrarith.rate;time.periodfloatnullablee_beta0(O-C)? rms uncertainty on beta0(O-C)0.001d.Myr**-1stat.errorintnullableu_beta0(O-C)Uncertainty flag on beta0(O-C) (1)meta.code.errorcharf_beta0(O-C)[*] * for recommended beta0 valuemeta.codecharbeta0(Pb)? Period change rate, dP/dt, from (P,beta)0.001d.Myr**-1meta.notefloatnullableu_beta0(Pb)? rms uncertainty on beta0(Pbeta)meta.code.errorcharf_beta0(Pb)[*] * for recommended beta0 valuemeta.codecharP0(Pb)? Period at E0 from (P,beta)dtime.perioddoublenullableNotesNotes (2)meta.notecharSimbadSimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/MNRAS/461/1032/table2aFundamental periods of studied starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVNameVariable namemeta.id;meta.maincharP0Period at E0dtime.perioddoubleE0Epoch (HJD)dtime.epochdoubleNobsNumber of observations in table2bmeta.numberintplotShow the O-C diagramsmeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/MNRAS/461/1032/table2bObserved times of maximum light O for RR Lyrae stars in M5 and the corresponding O-C residuals calculated with the given ephemerides for each variablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVNameVariable name (VNNN)meta.id;meta.maincharOObserved time of maximum light (JD-2400000)dtime.epochdoubleO-CO-C residualdstat.fit.residual;stat.fit.omcfloatNcyclesNumber of cycles elapsed between E0 and Cmeta.numberdoubleRefReference (1)meta.ref;pos.framechar