J/AJ/155/45ivo://CDS.VizieR/J/AJ/155/45doi:10.26093/cds/vizier.51550045CDSSneden C.Preston G.W.Kollmeier J.A.Crane J.D.Morrell N.,Prieto J.L.Shectman S.A.Skowron D.M.Thompson I.B.2018-12-03T14:47:07Z2018-10-03T12:45:38ZCDS support team

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

cds-question@unistra.frvariable-starsspectroscopymetallicityphotometryWe describe and employ a stacking procedure to investigate abundances derived from the low signal-to-noise ratio spectra obtained in the Carnegie RR Lyrae Survey (CARRS). We find iron metallicities that extend from [Fe/H]~-2.5 to values at least as large as [Fe/H]~-0.5 in the 274-spectrum CARRS RRc data set. We consider RRc sample contamination by high amplitude solar metallicity {delta} Scuti stars (HADS) at periods less than 0.3 days, where photometric discrimination between RRc and {delta} Scuti stars has proven to be problematic. We offer a spectroscopic discriminant, the well-marked overabundance of heavy elements, principally [Ba/H], that is a common, if not universal, characteristic of HADS of all periods and axial rotations. No bona fide RRc stars known to us have verified heavy-element overabundances. Three out of 34 stars in our sample with [Fe/H]>-0.7 exhibit anomalously strong features of Sr, Y, Zr, Ba, and many rare earths. However, carbon is not enhanced in these three stars, and we conclude that their elevated n-capture abundances have not been generated in interior neutron-capture nucleosynthesis. Contamination by HADS appears to be unimportant, and metal-rich RRc stars occur in approximately the same proportion in the Galactic field as do metal-rich RRab stars. An apparent dearth of metal-rich RRc is probably a statistical fluke. Finally, we show that RRc stars have a similar inverse period-metallicity relationship as has been found for RRab stars.2018AJ....155...45Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/155/45CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/264 : ASAS Variable Stars in Southern hemisphere (Pojmanski+, 2002-2005)J/AcA/48/35 : All Sky Automated Survey variable stars (Pojmamski 1998)J/AcA/50/177 : All Sky Automated Survey Catalog (Pojmanski+, 2000)J/MNRAS/358/30 : Automated classification of ASAS variables (Eyer+, 2005)J/MNRAS/377/1263 : Multiperiodic RR Lyrae in ASAS catalog (Szczygiel+, 2007)J/AcA/59/137 : ASAS Galactic fundamental mode RR Lyrae starsJ/ApJS/194/38 : Radial velocities of 11 field RR Lyrae (For+, 2011)J/ApJS/197/29 : Chemical compositions of 11 RR Lyrae (For+, 2011)J/ApJ/782/59 : Abundances of 8 RR Lyrae subclass C variable starsJ/MNRAS/445/1584 : AB-type RR Lyrae stars from ASAS and WASP (Skarka, 2014)http://www.astrouw.edu.pl/asas/ : ASAS catalog homepagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/155/45https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/155/45http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/155/45https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/155/45https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/155/45http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/155/45GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap3.322582951404819e-19 3.852589004194616e-19defaultJ/AJ/155/45/table1RRc Program StarsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintASASStar name in the ASAS Catalog (ASAS JHHMMSS+DDMM.m in Simbad)meta.id;meta.maincharn_ASAS[_12 ] Note on ASAS (1)meta.notecharPer[0.218941/0.42262] Pulsation period in the ASAS Catalogdmeta.iddoubleHJD0[1869.05/2788.84] Epoch of maximum light (HJD-2450000)dtime.epochdoubleVmax[8.16/13.63] Approximate V magnitude at maximum lightmagphot.mag;em.opt.VfloatVamp[0.05/1.4] Approximate V magnitude amplitudemagsrc.var.amplitude;em.opt.VfloatS/N[4.6/59.9] Mean signal-to-noise ratio near 4600 and 5200{AA}stat.snr;stat.meanfloat[Fe/H][-2.78/0.04] Metallicity estimate from Kollmeier et al. (2013ApJ...775...57K)log(Sun)phys.abund.ZfloatStack[1/28]? Number of co-added stack to which star belongsmeta.numberintnullablen_Stack[no ] Note on Stack (2)meta.notechar