Chemical abundances of solar neighborhood RR Lyrae stars

Abstract

We have analysed a sample of 18 RR Lyrae stars (17 fundamental-mode - RRab - and one first overtone - RRc) and three Population II Cepheids (two BL Her stars and one W Vir star), for which high-resolution (R $\ge$30000), high signal-to-noise (S/N$\ge$30) spectra were obtained with either SARG at the Telescopio Nazionale Galileo (La Palma, Spain) or UVES at the ESO Very Large Telescope (Paranal, Chile). Archival data were also analyzed for a few stars, sampling $\gtrsim$3 phases for each star. We obtained atmospheric parameters (T${}_{\mathrm{eff}}$, log$g$, v${}_{\mathrm{t}}$, and [M/H]) and abundances of several iron-peak and $\alpha$-elements (Fe, Cr, Ni, Mg, Ca, Si, and Ti) for different pulsational phases, obtaining $<$[$\alpha$/Fe]$>$=+0.31$\pm$0.19 dex over the entire sample covering -2.2$<$[Fe/H]$<$-1.1 dex. We find that silicon is indeed extremely sensitive to the phase, as reported by previous authors, and cannot be reliably determined. Apart from this, metallicities and abundance ratios are consistently determined, regardless of the phase, within 0.10-0.15 dex, although caution should be used in the range $0\lesssim \varphi \lesssim 0.15$. Our results agree with literature determinations for both variable and non-variable field stars, obtained with very different methods, including low and high-resolution spectroscopy. W Vir and BL Her stars, at least in the sampled phases, appear indistinguishable from RRab from the spectroscopic analysis point of view. Our large sample, covering all pulsation phases, confirms that chemical abundances can be obtained for RR Lyrae with the classical EW-based technique and static model atmospheres, even rather close to the shock phases.

arXiv comment16 pages, 8 figures, 7 tables (of which 1 electronic), accepted for publication on MNRAS

References in corpus (39)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Validation of the new Hipparcos reduction
• Northern Sky Variability Survey (NSVS): Public data release
• DAOSPEC: an automatic code for measuring equivalent widths in high-resolution stellar spectra
• Light Curve Templates and Galactic Distribution of RR Lyrae Stars from Sloan Digital Sky Survey Stripe 82
• Kinematics of Metal-Poor Stars in the Galaxy. II. Proper Motions for a Large Non-Kinematically Selected Sample
• Both accurate and precise gf-values for FeII lines
• Improved Laboratory Transition Probabilities for Neutral Chromium and Re-determination of the Chromium Abundance for the Sun and Three Stars
• Metal Abundances, Radial Velocities and other Physical Characteristics for the RR Lyrae Stars in the Kepler Field
• Abundances for metal-poor stars with accurate parallaxes II. alpha-elements in the halo
• Distance Scale Zero-Points from Galactic RR Lyrae Star Parallaxes
• The composition of HB stars : RR Lyrae variables
• The MACHO Project LMC Variable Star Inventory. IX. Frequency Analysis of the First Overtone RR Lyrae Stars and the Indication for Nonradial Pulsations
• Evidence for a Milky Way Tidal Stream Reaching Beyond 100 kpc
• The Konkoly Blazhko Survey: Is light-curve modulation a common property of RRab stars?
• Globular Cluster Distances from RR Lyrae Stars
• Analysis of RR Lyrae Stars in the Northern Sky Variability Survey
• GALA: an automatic tool for the abundance analysis of stellar spectra
• The Chemical Compositions of Variable Field Horizontal Branch Stars: RR Lyrae Stars
• A Consistency Test of Spectroscopic Gravities for Late-Type Stars
• Stellar evolution through the ages: period variations in galactic RRab stars as derived from the GEOS database and TAROT telescopes
• Tracing the Orphan Stream to 55 kpc with RR Lyrae Stars
• The Metallicity Dependence of the Fourier Components of RR Lyrae Light Curves is the Oosterhoff/Arp/Preston Period Ratio Effect in Disguise
• Spectroscopy of Bright QUEST RR Lyrae Stars: Velocity Substructures toward Virgo
• The Chemical Compositions of Non-Variable Red and Blue Field Horizontal Branch Stars
• RR Lyrae stars in Galactic globular clusters. VI. The Period-Amplitude relation
• The Chemical Compositions of the Type II Cepheids -- The BL Her and W Vir Variables
• The VMC Survey - X. Cepheids, RR Lyrae stars and binaries as probes of the Magellanic System's structure
• An In-Depth Spectroscopic Analysis of the Blazhko Star RR Lyr. I. Characterisation of the star: abundance analysis and fundamental parameters
• Statistical equilibrium of silicon in the atmospheres of metal-poor stars
• RR Lyrae Atmospherics: Wrinkles Old and New. A Preview
• Metal abundances of RR Lyrae stars in the metal rich globular cluster NGC 6441
• DOOp, an automated wrapper for DAOSPEC
• Proper identification of RR Lyrae Stars brighter than 12.5 mag
• Chemical abundances of metal-poor RR Lyrae stars in the Magellanic Clouds
• Metal Abundance Calibration of the Ca II Triplet Lines in RR Lyrae Stars
• An In-Depth Spectroscopic Analysis of RR Lyr Variations over the Pulsation Cycle
• A New CEMP-s RR Lyrae Star
• Axial rotation and turbulence of RR ab stars: the Peterson Conundrum revisited

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• Probing the galactic halo with RR Lyrae stars I: The catalog
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• On the use of field RR Lyrae as Galactic probes: IV. New insights into and around the Oosterhoff dichotomy
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• Chemical Compositions of Field and Globular Cluster RR Lyrae Stars: I. NGC 3201
• Chemical Compositions of Field and Globular Cluster RR~Lyrae Stars: II. omega Centauri
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• Relationship between the Elemental Abundances and the Kinematics of Galactic-Field RR Lyrae Stars
• Kinematics and Multi Band Period-Luminosity-Metallicity Relation of RR Lyrae Stars via Statistical Parallax
• Milky Way archaeology using RR Lyrae and type II Cepheids I. The Orphan stream in 7D using RR Lyrae stars
• Metal-Rich RRc stars in the Carnegie RR Lyrae Survey
• RR Lyrae stars as probes of the outer Galactic halo: Chemical and kinematic analysis of a pilot sample
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• Toward more accurate RR Lyrae metallicities
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