Metal Abundances, Radial Velocities, and Other Physical Characteristics for the RR Lyrae Stars in The Kepler Field
Spectroscopic iron-to-hydrogen ratios, radial velocities, atmospheric parameters, and new photometric analyses are presented for 41 RR Lyrae stars (and one probable high-amplitude δ Sct star) located in the field-of-view of the Kepler space telescope. Thirty-seven of the RR Lyrae stars are fundamental-mode pulsators (i.e., RRab stars) of which sixteen exhibit the Blazhko effect. Four of the stars are multiperiodic RRc pulsators oscillating primarily in the first-overtone mode. Spectroscopic [Fe/H] values for the 34 stars for which we were able to derive estimates range from –2.54 ± 0.13 (NR Lyr) to –0.05 ± 0.13 dex (V784 Cyg), and for the 19 Kepler-field non-Blazhko stars studied by Nemec et al. the abundances agree will with their photometric [Fe/H] values. Four non-Blazhko RR Lyrae stars that they identified as metal-rich (KIC 6100702, V2470 Cyg, V782 Cyg and V784 Cyg) are confirmed as such, and four additional stars (V839 Cyg, KIC 5520878, KIC 8832417, KIC 3868420) are also shown here to be metal-rich. Five of the non-Blazhko RRab stars are found to be more metal-rich than [Fe/H] ~–0.9 dex while all of the 16 Blazhko stars are more metal-poor than this value. New P-Ø_(31)^s-[Fe/H] relationships are derived based on ~970 days of quasi-continuous high-precision Q0-Q11 long- and short-cadence Kepler photometry. With the exception of some Blazhko stars, the spectroscopic and photometric [Fe/H] values are in good agreement. Several stars with unique photometric characteristics are identified, including a Blazhko variable with the smallest known amplitude and frequency modulations (V838 Cyg).
Additional Information© 2013 American Astronomical Society. Received 2013 March 25; accepted 2013 June 28; published 2013 August 6. Based in part on observations made at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Keck Observatory was made possible by the generous financial support of the W.M. Keck Foundation. Also, based in part on observations obtained at the Canada–France–Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National Des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. Funding for the Kepler Discovery mission is provided by NASA's Science Mission Directorate. The authors thank the entire Kepler team without whom these results would not be possible. We thank Nadine Mansett and her team of service observers at the Canada–France–Hawaii 3.6 m telescope for successfully acquiring the CFHT spectra. J.N. would like to thank Jozsef Benkõ, Johanna Jurcsik, Lászlo Molnár and Rόbert Szabό for discussions on Blazhko stars and for their hospitality at KASC5 and in Budapest. He also greatly appreciates discussions with Katrien Kolenberg regarding her RR Lyrae work, with Robert Stellingwerf concerning his PDM2 program, with BiQing for concerning the results of her PhD thesis, with Andrzej Pigulski for discussions about the ASAS-North survey. John Feldmeier sent information on the two BOKS survey RR Lyr stars, Géza Kovács kindly provided J.N. with his Fourier decomposition software, and Siobahn Morgan sent her file of Fourier parameters for RRc stars in galactic globular clusters. Finally, special thanks go to Amanda Linnell Nemec, Young-Beom Jeon, and Robert Szabό for their helpful comments on the manuscript, and to George Preston for his useful referee report. J.N. acknowledges support from the Camosun College Faculty Association; J.C. and B.S. acknowledge NSF grant AST-0908139; and P.M. is supported by Polish NCN grant DEC-2012/05/B/ST9/03932. This project has been supported by the Hungarian OTKA Grants K76816, K83790 an MB08C 81013 and the "Lendület-2009" Young Researchers Program of the Hungarian Academy of Sciences. A.D. was supported by the Hungarian Eötvös fellowship and by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences. Finally, all the authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community; we are most fortunate to have had the opportunity to conduct observations from this mountain. Facilities: CFHT, Keck:I, Kepler
Published - 0004-637X_773_2_181.pdf
Submitted - 1307.5820v1.pdf