A New CEMP-s RR Lyrae Star

Abstract

We show that SDSS J170733.93+585059.7 (hereafter SDSS J1707+58), previously identified by Aoki and collaborators as a carbon-enhanced metal-poor star (with s-process-element enhancements; CEMP-s), on the assumption that it is a main-sequence turn-off star, is the RR Lyrae star VIII-14 identified by the Lick Astrograph Survey. Revised abundances for SDSS J1707+58 are [Fe/H] = -2.92, [C/Fe] = +2.79, and [Ba/Fe] = +2.83. It is thus one of the most metal-poor RR Lyrae stars known, and has more extreme [C/Fe] and [Ba/Fe] than the only other RR Lyrae star known to have a CEMP-s spectrum (TY Gru). Both stars are Oosterhoff II stars with prograde kinematics, in contrast to stars with [C/Fe] < +0.7, such as KP Cyg and UY CrB, which are disk stars. Twelve other RR Lyrae stars with [C/Fe] >= +0.7 are presented as CEMP candidates for further study.

14 pages, 2 figures, accepted for publication in the Astrophysical Journal Letters

References in corpus (8)

• The stellar content of the Hamburg/ESO survey. IV. Selection of candidate metal-poor stars
• Carbon-Enhanced Metal-Poor Stars. III. Main-Sequence Turn-Off Stars from the SDSS/SEGUE Sample
• Evidence for Distinct Components of the Galactic Stellar Halo from 838 RR Lyrae Stars Discovered in the LONEOS-I Survey
• Analysis of RR Lyrae Stars in the Northern Sky Variability Survey
• Stellar evolution through the ages: period variations in galactic RRab stars as derived from the GEOS database and TAROT telescopes
• RR Lyrae stars in Galactic globular clusters. VI. The Period-Amplitude relation
• A Catalogue of RR Lyrae Stars from the Northern Sky Variability Survey
• Carbon-rich RR Lyr type stars

Cited by in corpus (8)

• Chemical abundances of solar neighborhood RR Lyrae stars
• The occurrence of nitrogen-enhanced metal-poor stars: implications for the initial mass function in the early Galactic halo
• Relationship between the Elemental Abundances and the Kinematics of Galactic-Field RR Lyrae Stars
• Seven New Carbon-Enhanced Metal-Poor RR Lyrae Stars
• Modelling the nucleosynthetic properties of carbon-enhanced metal-poor RR Lyrae stars
• A Very Metal-poor RR Lyrae Star with a Disk Orbit Found in the Solar Neighborhood
• NLTE CNO abundances in a sample of nine field RR lyr type stars
• CEMP-s and CEMP-s/r stars: last update