2006A&A...453..895W -
Astronomy and Astrophysics, volume 453, 895-902 (2006/7-3)
[Fe/H] derived from the light curves of RR Lyrae stars in the Galactic halo.
WU C., QIU Y.L., DENG J.S., HU J.Y. and ZHAO Y.H.
Abstract (from CDS):
The iron abundance of halo RR Lyrae stars can provide important information about the formation history of the Galactic halo. We determine the [Fe/H] of the sample of halo RRab stars by using the P-φ
31-[Fe/H] relation developed by Jurcsik & Kovacs (
1996A&A...312..111J) based on their light curves. We need to extend the relation from the V band to our unfiltered CCD band. To do this, we use the low-dispersion spectroscopic [Fe/H] of literatures and the photometric data released by the first-generation Robotic Optical Transient Search Experiment (ROTSE-I) project. We do regression analyses for the calibrating sample using a linear function and test its validity by comparing of the predicted [Fe/H] with the spectroscopic [Fe/H]. In general, the fit accuracy for the two different [Fe/H] is better than 0.19dex. We derive an empirical P-φ
31-[Fe/H] linear relation for the unfiltered CCD band (ROTSE-I), i.e. [Fe/H]=-3.766-5.350P+1.044φ
31. In our test, the P-φ
31-[Fe/H] relation is also fit for our unfiltered CCD band. In addition, another linear relation, φ
31V
=0.882+0.792φ31
W, is also derived for the transformation between the V and W bands. We present the predicted [Fe/H] of the sample (the 31 halo RRab stars) in a catalog. The mean [Fe/H] of the sample is -1.63 with dispersion of 0.45 dex in distribution, which is consistent with the results derived from the blue horizontal branch star candidates by Kinnman et al. (2000, A&A, 364, 102). The mean [Fe/H] values of the RRab stars in the range of 1 kpc, 2 kpc, and 3 kpc from the star 91 (a double-mode RR Lyrae star), are all lower than that of the background halo stars. These values are consistent with that of star 91 suggested by Wu et al. (
2005AJ....130.1640W), which indicates they might have a common origin.
Abstract Copyright:
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Journal keyword(s):
Galaxy: halo - stars: variables: RR Lyr - Galaxy: abundances
Simbad objects:
149
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