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http://hdl.handle.net/20.500.12386/24632
Titolo: | New Near-infrared Period-Luminosity-Metallicity Relations for RR Lyrae Stars and the Outlook for Gaia | Autori: | Muraveva, Tatiana Palmer, M. CLEMENTINI, Gisella Luri, X. Cioni, M. -R. L. Moretti, Maria Ida MARCONI, Marcella RIPEPI, Vincenzo RUBELE, STEFANO |
Data pubblicazione: | 2015 | Rivista: | THE ASTROPHYSICAL JOURNAL | Numero: | 807 | Fascicolo: | 2 | Da pagina:: | 127 | Abstract: | We present results of the analysis of 70 RR Lyrae stars located in the bar of the Large Magellanic Cloud (LMC). Combining the spectroscopically determined metallicity of these stars from the literature with precise periods from the OGLE III catalog and multi-epoch K<SUB>s</SUB> photometry from the VISTA survey of the Magellanic Clouds system, we derive a new near-infrared period-luminosity-metallicity ({{PL}}<SUB>{K</SUB><SUB>{{s</SUB>}}}{{Z}}) relation for RR Lyrae variables. In order to fit the relation we use a fitting method developed specifically for this study. The zero-point of the relation is estimated two different ways: by assuming the value of the distance to the LMC and by using Hubble Space Telescope parallaxes of five RR Lyrae stars in the Milky Way (MW). The difference in distance moduli derived by applying these two approaches is ̃0.2 mag. To investigate this point further we derive the {{PL}}<SUB>{K</SUB><SUB>{{s</SUB>}}}{{Z}} relation based on 23 MW RR Lyrae stars that had been analyzed in Baade-Wesselink studies. We compared the derived {{PL}}<SUB>{K</SUB><SUB>{{s</SUB>}}}{{Z}} relations for RR Lyrae stars in the MW and LMC. Slopes and zero-points are different, but still consistent within the errors. The shallow slope of the metallicity term is confirmed by both LMC and MW variables. The astrometric space mission Gaia is expected to provide a huge contribution to the determination of the RR Lyrae {{PL}}<SUB>{K</SUB><SUB>{{s</SUB>}}}{{Z}} relation; however, calculating an absolute magnitude from the trigonometric parallax of each star and fitting a {{PL}}<SUB>{K</SUB><SUB>{{s</SUB>}}}{{Z}} relation directly to period and absolute magnitude leads to biased results. We present a tool to achieve an unbiased solution by modeling the data and inferring the slope and zero-point of the relation via statistical methods. Based on observations made with VISTA at ESO under programme ID 179.B-2003. | Acknowledgments: | This work was supported by the Gaia Research for European Astronomy Training (GREAT-ITN) Marie Curie network, funded through the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement No. 264895. This work was also supported by the MINECO (Spanish Ministry of Economy)—FEDER through grant ESP2013-48318-C2-1R. We thank the Cambridge Astronomy Survey Unit (CASU) and the Wide Field Astronomy Unit (WFAU) in Edinburgh for providing calibrated data products under the support of the Science and Technology Facility Council (STFC) in the UK. We are grateful to P. Montegriffo for the development and maintenance of the GRATIS software. We thank the members of the OGLE team for making their catalogs public. | URI: | http://hdl.handle.net/20.500.12386/24632 | URL: | https://iopscience.iop.org/article/10.1088/0004-637X/807/2/127 | ISSN: | 0004-637X | DOI: | 10.1088/0004-637X/807/2/127 | Bibcode ADS: | 2015ApJ...807..127M | Fulltext: | open |
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