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**Session 81 - Variable Cool and Late Type Stars.**

*Display session, Wednesday, January 15*

*Metropolitan Ballroom, *

## [81.13] A Luminosity-[Fe/H] Relation for RR Lyrae Stars Derived from Fourier Parameters

*C. M. Clement (U. Toronto)*
Simon and Clement(1993, ApJ 410, 526) have used the technique of Fourier
decomposition of light curves to determine masses, luminosities and
temperatures for Bailey c type RR Lyrae (RRc) variables.
In an analysis of photographic data for RRc stars in six galactic globular
clusters (three of Oosterhoff type I and three of type II) they found that
mean masses and luminosities increase and mean temperatures decrease with
decreasing metal abundance. An analysis of CCD observations of RRc stars
in seven globular clusters (three of Oosterhoff type I and four of type II)
confirms Simon and Clement's earlier result. From this, we can derive an
M_V - [Fe/H] relation. Based on the the metallicity scale of Zinn (1985,
ApJ 293, 424), this relationship is M_V=0.27[\rmFe/H]+0.97. If the
metallicity scale of Jurcsik (1995, Acta A, 45, 653) is adopted instead,
the relationship is M_V=0.19[\rmFe/H]+0.82. The absolute magnitudes
derived from these two relationships are brighter than those derived from
M_V - [Fe/H] relations whose zero points are calibrated by statistical
parallaxes (Carney et al. 1992, ApJ 386, 663) or by the Baade-Wesselink
method (Kovács and Jurcsik 1996, ApJL 466, 17).

**Program
listing for Wednesday**