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The Baade-Wesselink method applied to RR Lyrae variables in the globular clusters M5 and M92

Cohen, J. G. (1992) The Baade-Wesselink method applied to RR Lyrae variables in the globular clusters M5 and M92. Astrophysical Journal, 400 . pp. 528-534. ISSN 0004-637X. doi:10.1086/172015.

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An infrared Baade-Wesselink analysis is given for two RR Lyrae variables in the extremely metal-poor globular cluster M92 and four in the intermediate metallicity cluster M5. The method of analysis relies on the theoretical model atmospheres of Kurucz and on the absolute flux calibration of observed V- and K-magnitudes. The best results are obtained with V-K colors to obtain T_(eff) and K-magnitudes to deduce absolute fluxes. We obtain a distance to M5 of 6.9 ± 0.45 kpc and to M92 of 7.85 ± 0.45 kpc, with a 0.3 kpc additional systematic uncertainty. These results are in excellent agreement with the previously published distances, based on matching the globular cluster main sequence to that defined by the field subdwarfs of known distance. With these distances we obtain an absolute mean magnitude corrected for reddening, M^0_v, of 0.86 ± 0.14 mag for the M5 RR Lyrae variables, while M^0_v= 0.62 ± 0.11 for the M92 RR Lyrae variables. The globular cluster RR Lyrae stars appear to behave just like the field RR Lyrae stars. They obey the same〈M_v〉- [Fe/H] relationship as do the field stars, and the same〈M_K〉-period relationship. Previous work which assumed the two groups of stars to behave identically is thus shown to be correct.

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Cohen, J. G.0000-0002-8039-4673
Additional Information:© American Astronomical Society • Provided by the NASA Astrophysics Data System. Received 1992 March 19; accepted 1992 June 4. I am grateful to Karen Lassey (a SURF student at Caltech) for help during the initial stages of this work. I am grateful to Gaston Araya Machining and the Caltech Recycling Center for financial support.
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Caltech Recycling CenterUNSPECIFIED
Subject Keywords:globular clusters: individual (M5, M92) - stars: variables: other (RR Lyr)
Record Number:CaltechAUTHORS:20190603-153224533
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96081
Deposited By: George Porter
Deposited On:04 Jun 2019 20:56
Last Modified:16 Nov 2021 17:17

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