On the Use of Field RR Lyrae as Galactic Probes. I. The Oosterhoff Dichotomy Based on Fundamental Variables Partially based on observations collected under ESO programs 297.D-5047 (PI: G. Bono) and 083.B-0281 (PI: D. Romano).
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Fecha
2019-09-10
Profesor/a Guía
Facultad/escuela
Idioma
en_US
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Título del volumen
Editor
Institute of Physics Publishing
Nombre de Curso
Licencia CC
ATRIBUCIÓN 4.0 INTERNACIONAL
Licencia CC
https://creativecommons.org/licenses/by/4.0/deed.es
Resumen
We collected a large data set of field RR Lyrae stars (RRLs) by using catalogs already available in the literature and Gaia DR2. We estimated the iron abundances for a subsample of 2382 fundamental RRLs (ΔS method: Ca ii K, Hβ, Hγ, and Hδ lines) for which there are publicly available medium-resolution SDSS-SEGUE spectra. We also included similar estimates available in the literature, ending up with the largest and most homogeneous spectroscopic data set ever collected for RRLs (2903). The metallicity scale was validated by using iron abundances based on high-resolution spectra for a fundamental field RRL (V Ind), for which we collected X-shooter spectra covering the entire pulsation cycle. The peak ([Fe/H] =-1.59 ± 0.01) and the standard deviation (σ = 0.43 dex) of the metallicity distribution agree quite well with similar estimates available in the literature. The current measurements disclose a well-defined metal-rich tail approaching solar iron abundance. The spectroscopic sample plotted in the Bailey diagram (period versus luminosity amplitude) shows a steady variation when moving from the metal-poor ([Fe/H] =-3.0/-2.5) to the metal-rich ([Fe/H] =-0.5/0.0) regime. The smooth transition in the peak of the period distribution as a function of the metallicity strongly indicates that the long-standing problem of the Oosterhoff dichotomy among Galactic globular clusters is the consequence of the lack of metal-intermediate clusters hosting RRLs. We also found that the luminosity amplitude, in contrast with period, does not show a solid correlation with metallicity. This suggests that period-amplitude-metallicity relations should be cautiously treated.
Notas
Indexación: Scopus.
Palabras clave
Galaxy: Halo-stars: Variables: Rr lyrae-techniques: Spectroscopic
Citación
Astrophysical Journal Volume 882, Issue 2 10 September 2019 Article number 169
DOI
10.3847/1538-4357/ab3977