Studies of extragalactic RR Lyrae stars
RR Lyrae stars in and around the LMC halo globular cluster NGC 2257 are identified and photometrically studied. In the cluster 41 RR Lyrae stars are known, with = 0/sup d/583(16 stars), = 0./sup d/353(22 stars), and P/sub ab,min/ - 0./sup d/493. NGC 2257 appears to be one of the few known systems having an intermediate (i.e., I-II) Oosterhoff type. The value derived for Fe/H is -1.8 +/- 0.3. Mean magnitudes suggest that NGC 2257 is approx.4 Kpc in front of the LMC disk. The identification of two large amplitude, short period RRab stars suggests that the field around NGC 2257 contains stars of higher Fe/H than does the cluster, and that the field has a wide range of Fe/H. Ten double-mode RR Lyrae (RRd) stars were identified in the Draco dwarf galaxy. Beat mass and metal abundance ranges are found from 0.55 to 0.65 solar mass, and from (Fe/H)/sub M3/ to (Fe/H)/sub M15/. In most respects the stars are indistinguishable from Galactic RRd stars.
- Research Organization:
- Washington Univ., Seattle (USA)
- OSTI ID:
- 5413240
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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