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|Title:||On a New Theoretical Framework for RR Lyrae Stars. I. The Metallicity Dependence||Authors:||MARCONI, Marcella
Stellingwerf, R. F.
Braga, Vittorio Francesco
|Issue Date:||2015||Journal:||THE ASTROPHYSICAL JOURNAL||Number:||808||Issue:||1||First Page:||50||Abstract:||We present new nonlinear, time-dependent convective hydrodynamical models of RR Lyrae stars computed assuming a constant helium-to-metal enrichment ratio and a broad range in metal abundances (Z = 0.0001-0.02). The stellar masses and luminosities adopted to construct the pulsation models were fixed according to detailed central He-burning horizontal-branch evolutionary models. The pulsation models cover a broad range in stellar luminosity and effective temperatures and the modal stability is investigated for both fundamental (FU) and first overtone polsators (FOs). We predict the topology of the instability strip (IS) as a function of the metal content and new analytical relations for the edges of the IS in the observational plane. Moreover, a new analytical relation to constrain the pulsation mass of double pulsators as a function of the period ratio and the metal content is provided. We derive new Period-Radius-Metallicity relations for FU and FO pulsators. They agree quite well with similar empirical and theoretical relations in the literature. From the predicted bolometric light curves, transformed into optical (UBVRI) and near-infrared (NIR; JHK) bands, we compute the intensity-averaged mean magnitudes along the entire pulsation cycle and in turn new and homogenous metal-dependent (RIJHK) Period-Luminosity relations. Moreover, we compute new dual and triple-band optical, optical-NIR, and NIR Period-Wesenheit-Metallicity relations. Interestingly, we find that the optical Period-W(V, B-V) is independent of the metal content and that the accuracy of individual distances is a balance between the adopted diagnostics and the precision of photometric and spectroscopic data sets.||Acknowledgments:||It is a pleasure to acknowledge the anonymous referee for positive encouragment concerning our investigations and for pertinent comments and suggestions that improved the content and the size of the current manuscript. This work was partially supported by PRIN-INAF 2011 “Tracing the formation and evolution of the Galactic halo with VST” (P.I.: M. Marconi), by PRIN-INAF 2012 “The M4 Core Project with Hubble Space Telescope ” (P.I.: L. Bedin), and by PRIN-MIUR (2010LY5N2T) “Chemical and dynamical evolution of the Milky Way and Local Group galaxies” (P.I.: F. Matteucci). G.B. thanks The Carnegie Observatories visitor program for support as a science visitor.||URI:||http://hdl.handle.net/20.500.12386/23516||URL:||https://iopscience.iop.org/article/10.1088/0004-637X/808/1/50||ISSN:||0004-637X||DOI:||10.1088/0004-637X/808/1/50||Bibcode ADS:||2015ApJ...808...50M||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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checked on Oct 27, 2020
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