J/AJ/144/88ivo://CDS.VizieR/J/AJ/144/88doi:10.26093/cds/vizier.51440088CDSHaschke R.Grebel E.K.Frebel A.Duffau S.Hansen C.J.Koch A.2017-06-21T08:21:52Z2013-10-29T07:57:57ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsvariable-starsline-intensitiesmetallicityradial-velocityWe present for the first time a detailed spectroscopic study of chemical element abundances of metal-poor RR Lyrae stars in the Large and Small Magellanic Cloud (LMC and SMC). Using the MagE echelle spectrograph at the 6.5m Magellan telescopes, we obtain medium resolution (R~2000-6000) spectra of six RR Lyrae stars in the LMC and three RR Lyrae stars in the SMC. These stars were chosen because their previously determined photometric metallicities were among the lowest metallicities found for stars belonging to the old populations in the Magellanic Clouds. We find the spectroscopic metallicities of these stars to be as low as [Fe/H]_spec_=-2.7dex, the lowest metallicity yet measured for any star in the Magellanic Clouds. We confirm that for metal-poor stars, the photometric metallicities from the Fourier decomposition of the light curves are systematically too high compared to their spectroscopic counterparts. However, for even more metal-poor stars below [Fe/H]_phot_<-2.8dex this trend is reversed and the spectroscopic metallicities are systematically higher than the photometric estimates. We are able to determine abundance ratios for 10 chemical elements (Fe, Na, Mg, Al, Ca, Sc, Ti, Cr, Sr, and Ba), which extend the abundance measurements of chemical elements for RR Lyrae stars in the Clouds beyond [Fe/H] for the first time. For the overall [{alpha}/Fe] ratio, we obtain an overabundance of 0.36dex, which is in very good agreement with results from metal-poor stars in the Milky Way halo as well as from the metal-poor tail in dwarf spheroidal galaxies. Comparing the abundances with those of the stars in the Milky Way halo we find that the abundance ratios of stars of both populations are consistent with another. Therefore, we conclude that from a chemical point of view early contributions from Magellanic-type galaxies to the formation of the Galactic halo as claimed in cosmological models are plausible.2012AJ....144...88Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/144/88CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/197/29 : Chemical compositions of 11 RR Lyrae (For+, 2011)J/AJ/142/61 : RGB stars in LMC outer disk (Carrera+, 2011)J/ApJ/717/277 : Chemical composition of old LMC clusters (Mucciarelli+, 2010)J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010)J/AcA/60/165 : VI light curves of SMC RR Lyrae (Soszynski+, 2010)J/A+A/501/519 : Extremely metal-poor turnoff stars abundancesJ/AcA/59/1 : VI light curves of LMC RR Lyrae stars (Soszynski+, 2009)J/A+A/480/379 : Abundances of 59 red giants in LMC (Pompeia+, 2008)J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)J/AJ/135/836 : Calcium triplet index in LMC stars (Carrera+, 2008)J/AJ/136/1039 : CaII index of SMC red giant branch stars (Carrera+, 2008)J/AJ/132/85 : Equivalent width of 33 metal-poor RHB (Preston+, 2006)J/A+A/460/459 : Radial velocities of LMC RR Lyrae (Borissova+, 2006)J/AJ/129/1465 : Spectroscopy of red giants in the LMC bar (Cole+, 2005)J/AJ/128/1177 : Galactic stellar abundances (Venn+, 2004)J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)J/A+A/421/937 : Metal abundances of LMC RR Lyrae (Gratton+, 2004)J/A+A/423/97 : LMC RR Lyrae radial velocities (Borissova+, 2004)J/A+A/403/1105 : Extremely metal-poor giants equivalent widthsJ/AcA/53/93 : OGLE RR Lyrae in LMC (Soszynski+, 2003)J/AJ/115/193 : RR Lyrae V light curves (Layden, 1998)J/AJ/110/2319 : Abundances in RR Lyr variables (Clementini+ 1995)J/AJ/108/1016 : Kinematics of local RR lyrae stars. I. (Layden, 1994)J/A+A/290/885 : Abundances of very metal-poor stars (Primas+, 1994)http://ogle.astrouw.edu.pl/ : OGLE surveyhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/144/88https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/144/88http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/144/88https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/144/88https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/144/88http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/144/88GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/144/88/stars (Properties of RR Lyrae stars observed with Magellan/MagE, and metal-poor standard stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/144/88/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/144/88/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/144/88/stars?GETtext/xml+votable180.050000true130.2116667-16.34513890.0055555555555555566/110 26025 33052 33084 33094 33097 33098 33123 33295 33316 33317 40567https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/144/88?format=asciiOpticaldefaultJ/AJ/144/88/starsProperties of RR Lyrae stars observed with Magellan/MagE, and metal-poor standard starsSimbadNameSimbad column added by the CDSmeta.idcharPerPerioddtime.perioddoublenullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarName of the RR Lyrae star (1)meta.id;meta.maincharprimaryf_StarFlag on Star (a = the observation of RR8645 contains a second, originally not targeted, star in the slit)meta.codecharVmag[18.78/20.21] V-band magnitudemagphot.mag;em.opt.VfloatRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainDateUT date of observationtime.epoch;obsnullableN[1/4] Number of integrationsmeta.numberintnullableExpExposition timestime.duration;obs.exposureintnullableSlit[0.7/2] Slit used for the spectra (2)arcsecinstr.setupfloatnullable[Fe/H]p[-3.5/-2.0] Photometric metallicitylog(Sun)phys.abund.ZfloatnullableBlBlazhko effect? (yes or no)meta.codecharRVh[-40/325] Median heliocentric systemic radial velocitykm/sspect.dopplerVeloc;stat.medianintnullableRVl[-51/309] Systemic radial velocity in the local standard of rest (LSR)km/sspect.dopplerVeloc;pos.lsrintnullablePhaseMean phase of the observationtime.phasefloatnullablesrStandard deviation of the radial velocity measurements ({sigma}_r_)km/sstat.errorintnullablesyUncertainty of the systemic velocity ({sigma}_{gamma}_)km/sstat.errorintnullableTeffDerived effective temperatureKphys.temperature.effectiveintloggDerived surface graitylog(cm.s**-2)phot.sbfloat[Fe/H][-3.1/-1.9] Derived metallicitylog(Sun)phys.abund.ZfloatvtMicroturbulence velocity {xi}km/sphys.veloc.microTurbfloatMCMagellanic cloud (LMC or SMC)meta.codecharcolstarName(s) of columns with equivalent sidths in table4meta.noteJ/AJ/144/88/table4Equivalent width measurements for all target and standard starsElName of ionmeta.id;phys.atmol.ionStagecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintZAtomic number and ionisationphys.atmol.number;phys.atmol.ionizationfloatlambdaWavelength {lambda} ({AA})0.1nmem.wlfloatEPExcitation potentialeVphys.atmol.excitationfloatloggfLog of the oscillator strengthphys.atmol.oscStrengthfloatHD74000(1)? Equivalent width of HD74000 (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullableHD74000(2)? Equivalent width of HD74000 (m{AA}) (2)1e-13mspect.line.eqWidthfloatnullableHD74000(3)? Equivalent width of HD74000 (m{AA}) (3)1e-13mspect.line.eqWidthfloatnullableXAri(1)? Equivalent width of X Ari; (m{AA}) (1)1e-13mspect.line.eqWidth;em.X-rayfloatnullableXAri(4)? Equivalent width of X Ari; (m{AA}) (4)1e-13mspect.line.eqWidth;em.X-rayfloatnullableG64-12(1)? Equivalent width of G64-12; (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullableRR15903? Equivalent width of RR 15903 (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullableRR8645? Equivalent width of RR 8645 (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullableRR1422? Equivalent width of RR 1422 (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullableRR177? Equivalent width of RR 177 (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullableRR11371? Equivalent width of RR 11371 (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullableRR22827? Equivalent width of RR 22827 (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullableRR122432? Equivalent width of RR 122432 (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullableRR50180? Equivalent width of RR 50180 (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullableRR143874? Equivalent width of RR 143874 (m{AA}) (1)1e-13mspect.line.eqWidthfloatnullable