Toward more accurate RR Lyrae metallicities

Abstract

By using a large sample of published spectroscopic iron abundances, we point out the importance of gravity correction in deriving more accurate metal abundances for RR Lyrae stars. For the 197 stars with multiple spectra we find overall [Fe/H] standard deviations of 0.167 (as published), 0.145 (shifted by data source zero points) and 0.121 (both zero point-shifted and gravity-corrected). These improvements are significant at the ~2 sigma level at each correction step, leading to a clearly significant improvement after both corrections applied. The higher quality of the gravity-corrected metallicities is strongly supported also by the tighter correlation with the metallicities predicted from the period and Fourier phase phi_31. This work underlines the need for using some external estimates of the temporal gravity in the chemical abundance analysis rather than relying on a full-fetched spectrum fit that leads to large correlated errors in the estimated parameters.

arXiv commentSubmitted to A&A. After the 2nd (less negative/almost positive) referee report. 1.2Mb, 10 pages (7+3 with appendices). Aesthetic old-fashioned references with clickable ADS links

References in corpus (26)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• Gaia Early Data Release 3: The astrometric solution
• The GALAH+ Survey: Third Data Release
• The unWISE Catalog: Two Billion Infrared Sources from Five Years of WISE Imaging
• Stellar Iron Abundances: non-LTE Effects
• Abundance Estimates for 16 Elements in 6 Million Stars from LAMOST DR5 Low-Resolution Spectra
• Accuracy and precision of industrial stellar abundances
• A pulsational approach to near infrared and visual magnitudes of RR Lyrae stars
• Metal Abundances, Radial Velocities and other Physical Characteristics for the RR Lyrae Stars in the Kepler Field
• RR Lyrae stars as standard candles in the Gaia Data Release 2 Era
• The composition of HB stars : RR Lyrae variables
• HAT-P-6b: A Hot Jupiter transiting a bright F star
• The Chemical Compositions of Variable Field Horizontal Branch Stars: RR Lyrae Stars
• Spectroscopic Comparison of Metal-Rich RRab Stars of the Galactic Field with Their Metal-Poor Counterparts
• The ASAS-SN Catalog of Variable Stars X: Discovery of 116,000 New Variable Stars Using g-band Photometry
• Photometric metallicity and distance estimates for $\sim$ 136,000 RR Lyrae stars from Gaia DR3
• Chemical abundances of solar neighborhood RR Lyrae stars
• APOGEE Net: An expanded spectral model of both low mass and high mass stars
• On the Use of Field RR Lyrae as Galactic Probes. III. The $\alpha$-element abundances
• Metallicities from high resolution spectra of 49 RR Lyrae Variables
• Probing galactic double-mode RR Lyrae stars against Gaia EDR3
• Pulsational and evolutionary analysis of the double-mode RR Lyrae star BS Com
• NLTE CNO abundances in a sample of nine field RR lyr type stars
• Surface C, N, O, and Na abundances of RR Lyrae variables implying the nature of internal mixing in low-mass stars
• Bright single-mode RR Lyrae stars: matching Gaia EDR3 with pulsation and evolutionary models