The period-magnitude diagram of RR Lyrae stars -- I. The controversy about the distance scale
- 1 February 1997
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 284 (4) , 994-1000
- https://doi.org/10.1093/mnras/284.4.994
Abstract
Convective pulsating models with surface helium abundances of Y=0.24 and total masses of M= 0.58,0.65 and 0.75 M⊙ are used to predict the limits of the distribution of RR Lyrae stars with a given mass in the period-absolute magnitude plane. On this basis, data of RR Lyrae stars in well-studied Galactic globular clusters clearly contradict the so-called ‘long distance scale’ for calibrating the RR Lyrae absolute magnitude in terms of metal content {Mv(RR)=0.94 +0.30 [Fe/H]}, in that most c-type variables turn out to fall in the hot stable region, outside the RR Lyrae instability strip. Conversely, if the calibration of Mv(RR) follows the precepts of stellar evolution theory, then a close agreement with the pulsational constraints is obtained.Keywords
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