On the use of field RR Lyrae as galactic probes. IV: New insights into and around the Oosterhoff dichotomy

Autor: Peter B. Stetson, Massimo Marengo, E. Valenti, C. K. Gilligan, J. P. Mullen, Jillian R. Neeley, P. M. Marrese, Matteo Monelli, George W. Preston, I. Ferraro, H. Lala, Maurizio Salaris, Vittorio F. Braga, Brian Chaboyer, R. da Silva, Giuseppe Bono, Eva K. Grebel, Z. Prudil, Manuela Zoccali, Giuliana Fiorentino, Mario Nonino, S. Marinoni, G. Altavilla, Christopher Sneden, Noriyuki Matsunaga, G. Iannicola, J. Crestani, M. Fabrizio, B. Lemasle, D. Magurno, C. E. Martínez-Vázquez, Massimo Dall'Ora, Frédéric Thévenin
Přispěvatelé: Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: The Astrophysical Journal
The Astrophysical Journal, American Astronomical Society, 2021, 919 (2), pp.118. ⟨10.3847/1538-4357/ac1115⟩
ISSN: 0004-637X
1538-4357
DOI: 10.3847/1538-4357/ac1115⟩
Popis: We discuss the largest and most homogeneous spectroscopic dataset of field RR Lyrae variables (RRLs) available to date. We estimated abundances using both high-resolution and low-resolution ({\Delta S} method) spectra for fundamental (RRab) and first overtone (RRc) RRLs. The iron abundances for 7,941 RRLs were supplemented with similar literature estimates available, ending up with 9,015 RRLs (6,150 RRab, 2,865 RRc). The metallicity distribution shows a mean value of = -1.51\pm0.01, and {\sigma}(standard deviation)= 0.41 dex with a long metal-poor tail approaching [Fe/H] = -3 and a sharp metal-rich tail approaching solar iron abundance. The RRab variables are more metal-rich (ab = -1.48\pm0.01, {\sigma} = 0.41 dex) than RRc variables (c = -1.58\pm0.01, {\sigma} = 0.40 dex). The relative fraction of RRab variables in the Bailey diagram (visual amplitude vs period) located along the short-period (more metal-rich) and the long-period (more metal-poor) sequences are 80% and 20\%, while RRc variables display an opposite trend, namely 30\% and 70\%. We found that the pulsation period of both RRab and RRc variables steadily decreases when moving from the metal-poor to the metal-rich regime. The visual amplitude shows the same trend, but RRc amplitudes are almost two times more sensitive than RRab amplitudes to metallicity. We also investigated the dependence of the population ratio (Nc/Ntot) of field RRLs on the metallicity and we found that the distribution is more complex than in globular clusters. The population ratio steadily increases from ~0.25 to ~0.36 in the metal-poor regime, it decreases from ~0.36 to ~0.18 for -1.8 < [Fe/H] < -0.9 and it increases to a value of ~0.3 approaching solar iron abundance.
Comment: 22 pages, 13 figures, 3 tables. Accepted for publication in ApJ
Databáze: OpenAIRE
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