J/ApJ/908/20ivo://CDS.VizieR/J/ApJ/908/20doi:10.26093/cds/vizier.19080020CDSCrestani J.Fabrizio M.Braga V.F.Sneden C.Preston G.Ferraro I.,Iannicola G.Bono G.Alves-Brito A.Nonino M.D'Orazi V.Inno L.,Monelli M.Storm J.Altavilla G.Chaboyer B.Dall'Ora M.Fiorentino G.,Gilligan C.Grebel E.K.Lala H.Lemasle B.Marengo M.Marinoni S.,Marrese P.M.Martinez-Vazquez C.E.Matsunaga N.Mullen J.P.Neeley J.,Prudil Z.da Silva R.Stetson P.B.Thevenin F.Valenti E.Walker A.,Zoccali M.2022-08-26T08:25:48Z2022-07-27T12:13:38ZCDS support team

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

cds-question@unistra.frvariable-starsvisible-astronomyspectroscopyinfrared-astronomymetallicityeffective-temperatureWe performed the largest and most homogeneous spectroscopic survey of field RR Lyraes (RRLs). We secured ~6300 high-resolution (HR, R~35000) spectra for 143 RRLs (111 fundamental, RRab; 32 first-overtone, RRc). The atmospheric parameters were estimated by using the traditional approach and the iron abundances were measured by using an LTE line analysis. The resulting iron distribution shows a well-defined metal-rich tail approaching solar iron abundance. This suggests that field RRLs experienced a complex chemical enrichment in the early halo formation. We used these data to develop a new calibration of the {Delta}S method. This diagnostic, based on the equivalent widths of Ca^II^K and three Balmer (H{delta},{gamma},{beta}) lines, traces the metallicity of RRLs. For the first time, the new empirical calibration: (I) includes spectra collected over the entire pulsation cycle; (II) includes RRc variables; (III) relies on spectroscopic calibrators covering more than three dex in iron abundance; and (IV) provides independent calibrations based on one/two/three Balmer lines. The new calibrations were applied to a data set of both SEGUE-SDSS and degraded HR spectra totalling 6451 low-resolution (R~2000) spectra for 5001 RRLs (3439 RRab, 1562 RRc). This resulted in an iron distribution with a median {eta}=-1.55{+/-}0.01 and {sigma}=0.51dex, in good agreement with literature values. We also found that RRc are 0.10dex more metal-poor than RRab variables, and have a distribution with a smoother metal-poor tail. This finding supports theoretical prescriptions suggesting a steady decrease in the RRc number when moving from metal-poor to metal-rich stellar environments.2021ApJ...908...20Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/908/20CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/264 : ASAS Variable Stars in Southern hemisphere (Pojmanski+, 2002-2005)II/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020)J/AJ/108/1016 : Kinematics of local RR lyrae stars. I. (Layden, 1994)J/AJ/110/2319 : Abundances in RR Lyr variables (Clementini+ 1995)J/A+AS/121/327 : RR Lyr pulsational model (Bono+ 1997)J/A+A/421/937 : Metal abundances of LMC RR Lyrae (Gratton+, 2004)J/MNRAS/396/553 : Galactic RR Lyrae data (Dambis, 2009)J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)J/ApJS/197/29 : Chemical compositions of 11 RR Lyrae (For+, 2011)J/MNRAS/435/3206 : Properties of field RR Lyrae variables (Dambis+, 2013)J/ApJ/763/32 : Galactic halo RRab stars from CSS (Drake+, 2013)J/ApJ/765/154 : RR Lyrae stars in the Catalina Sky Survey (Drake+, 2013)J/ApJS/215/23 : FeI radiative lifetime & branching fractions (Den Hartog+,2014)J/ApJ/782/59 : Abundances 8 RR Lyrae subclass C variable stars (Govea+, 2014)J/MNRAS/441/3127 : FeI oscillator strengths for Gaia-ESO (Ruffoni+, 2014)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/MNRAS/447/2404 : Equivalent width of 21 RR Lyrae stars (Pancino+, 2015)J/MNRAS/446/2251 : Southern Catalina Survey type-ab RR Lyrae (Torrealba+, 2015)J/AJ/152/170 : RRLs in globulars. IV. UBVRI photometry OmegaCen (Braga+, 2016)J/MNRAS/469/3688 : CSS Periodic Variable Star Catalogue (Drake+, 2017)J/AJ/153/204 : RR Lyrae stars from the PS1 3{pi} survey (Sesar+, 2017)J/ApJ/848/68 : Abundances & RVs of stable & Blazhko RRc stars (Sneden+, 2017)J/AJ/155/137 : RRLs in globulars. V.{omega} Centauri NIR photo. (Braga+, 2018)J/ApJ/864/57 : Abundances of field & GC RR Lyrae. I. NGC3201 (Magurno+, 2018)J/ApJ/870/115 : Reddening, distance modulus & Fe/H RRLs in wCen (Bono+, 2019)J/ApJ/881/104 : Spectroscopic obs. of RR Lyrae in NGC5139 (Magurno+, 2019)J/AJ/158/16 : Identification of RR Lyrae stars from the DES (Stringer+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/908/20https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/908/20http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/908/20https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/908/20https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/908/20http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/908/20GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/908/20/table1 (Identification, photometric characteristics, classification, and number of spectra for the CHR)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/908/20/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/908/20/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/908/20/table1?GETtext/xml+votable180.050000true309.5628181-2.89028220.0055555555555555566/110 553 572 4479 8294 8466 8773 10328 10602 11123 12512 12576 12696 12743 16602 16867 16923 16934 17328 17745 17748 18177 18303 18536 18633 19104 19110 19333 21127 21131 21146 21182 24590 24602 24614 24621 24623 24724 24772 24866 24913 25120 25199 25611 25768 25803 25879 25953 26131 26281 26288 26756 26807 26981 27047 27260 27279 27333 27824 28040 28813 30019 30055 30868 30923 31335 31390 31498 31589 31648 31743 31787 33465 33996 34407 34491 34537 34606 34944 35151 35423 35629 35652 35678 35686 35714 35758 35944 36605 36704 38259 38360 38456 38809 39152 39767 40475 40767 40924 40952 40988 40998 41022 41260 41318 42007 42053 42068 42260 42672 43387 44832 44914 44924 45324 45337 45994 46069 46075 46130 46373 46396 46464 46482 46650 46686 46824 47074 47342 47446 47467 47856 48113 48228 48290 48459 48576 48715 48911 48916 49011 49102https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/908/20?format=asciiOpticalInfrareddefaultJ/ApJ/908/20/table1Identification, photometric characteristics, classification, and number of spectra for the CHRSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaGaia DR2 identificationmeta.id;meta.mainprimaryNameObject namemeta.idcharRAdeg[0.7/355] Right ascension (J2000)degpos.eq.raDEdeg[-85/57] Declination (J2000)degpos.eq.decVmag[8.96/17.3] Mean V-band magnitudemagphot.mag;em.opt.VfloatVamp[0.25/1.84] V-band amplitudemagphot.magfloatPer[0.21/0.96] Perioddtime.perioddoubleClassPulsation modesrc.classcharBlazhkoBlazhko modulationmeta.crypticcharN[1/365] Number of spectrameta.numberfloat_RAPosition from SIMBAD (right ascension part)degpos.eq.ra;meta.main_DEPosition from SIMBAD (declination part)degpos.eq.dec;meta.mainJ/ApJ/908/20/table2Atmospheric parameters derived in this work for each individual measurementNFeI[9/234] Number of neutral FeI linesmeta.numberintNameObject namemeta.numbercharClassPulsation modesrc.classcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaGaia DR2 identificationmeta.id;meta.mainSpectSpectrograph identificationmeta.notecharTeff[5750/8210] Effective temperatureKphys.temperature.effectiveinte_Teff[0/940] Uncertainty in TeffKstat.error;phys.temperature.effectiveintlogg[0.79/4] Surface gravityphys.gravityfloate_logg[0.04/0.5] Uncertainty in loggstat.errordoubleVt[1.19/5.82] Microturbulent velocitykm/sphys.velocfloate_Vt[0.05/2.5] Uncertainty in Vtkm/sstat.errordoublee_[FeI/H][0.06/0.3] Uncertainty in [FeI/H]stat.error;phys.abundfloat[FeI/H][-3.12/0.18] Median Solar-scaled FeI abundance of neutral iron linesphys.abund.Fe;stat.mediandouble[FeII/H][-3.12/0.18] Median Solar-scaled FeII abundance of singly ionized iron linesphys.abund.Fe;stat.mediandoublee_[FeII/H][0.01/0.9] Uncertainty [FeII/H]stat.error;phys.abundfloatNFeII[2/39] Number of singly ionized FeII linesmeta.numberintJ/ApJ/908/20/table3List of FeI and FeII lines adopted in this work for the determination of atmospheric parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWave[3763/8847] Vacuum wavelength0.1nmem.wlfloatSpecies[26/27] Speciesmeta.notefloatEP[0/6.23] Excitation potentialeVphys.atmol.excitationfloatloggf[-6.48/0.65] Oscillator strengthphys.atmol.oscStrengthfloatRefLine parameters reference (1)meta.refcharJ/ApJ/908/20/table5Adopted metallicities and uncertainties for each individual star in the CHR sample.GaiaGaia DR2 identificationmeta.id;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameObject namemeta.idcharClassPulsation modesrc.classchar[Fe/H][-3.06/0.13] Solar-scaled metallicityphys.abund.Zfloate_[Fe/H][0/0.3] Uncertainty in [Fe/H]stat.error;phys.abund.FefloatRefReference code for [Fe/H] (1)meta.notecharJ/ApJ/908/20/table7Individual measurements of the equivalent widths of interest for the CHR sampleGaiaGaia DR identificationmeta.id;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[2452007/2458743] Heliocentric Julian Datedtime.epochdoubleCaIIK[0.01/7.71] Equivalent width of CaII K line0.1nmspect.line.eqWidthdoublee_CaIIK[0/14688] Uncertainty in CaIIK0.1nmstat.errordoubleHd[-9.01/9.71] Equivalent width of H{delta} line0.1nmspect.line.eqWidthdoublee_Hd[0.05/261] Uncertainty in Hd0.1nmstat.errordoubleHg[0.07/9.57] Equivalent width of H{gamma} line0.1nmspect.line.eqWidthdoublee_Hg[0.05/1592] Uncertainty in Hg0.1nmstat.errordoubleHb[0.09/8.17] Equivalent width of H{beta} line0.1nmspect.line.eqWidthdoublee_Hb[0.02/594] Uncertainty in Hb0.1nmstat.errordoubleJ/ApJ/908/20/table9The [Fe/H]{Delta}S measurements for the CHR sampleGaiaGaia DR2 identificationmeta.id;meta.maindS(HdHg)[-2.45/-0.2] Median dS considering H{delta}, H{gamma}src.sample;stat.mediandoublee_dS(HdHg)[0/0.59] Uncertainty in dS(Hd,Hg)stat.errordoubledS(HdHb)[-2.74/0.08] Median dS considering H{delta}, H{beta}src.sample;stat.mediandoublee_dS(HdHb)[0/0.63] Uncertainty in dS(Hd,Hb)stat.errordoubledS(HgHb)[-2.73/-0.04] Median dS considering H{gamma}, H{beta}src.sample;stat.mediandoublee_dS(HgHb)[0/0.61] Uncertainty in dS(Hg,Hb)stat.errordoubledS(Hd)[-2.44/-0.21] Median dS considering H{delta}src.sample;stat.mediandoublee_dS(Hd)[0/0.45] Uncertainty in dS(Hd)stat.errordoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNspec[1/365] Number of spectrameta.numberfloatdS(HdHgHb)[-2.74/0.08] Median dS considering H{delta}, H{gamma}, H{beta}src.sample;stat.mediandoublee_dS(HdHgHb)[0/0.63] Uncertainty indS(Hd,Hg,Hb)stat.errordoubledS(Hg)[-2.46/-0.18] Median dS considering Hgsrc.sample;stat.mediandoublee_dS(Hg)[0/0.48] Uncertainty in dS(Hg)stat.errordoubledS(Hb)[-2.62/-0.14] Median dS considering Hbsrc.sample;stat.mediandoublee_dS(Hb)[0/0.48] Uncertainty in dS(Hb)stat.errordoubleClassPulsation modesrc.classchar