Studies of extragalactic RR Lyrae stars
= 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
- Country of Publication:
- United States
- Language:
- English
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CCD photometry of the RR Lyrae variables in the LMC cluster NGC 2257 and the adjacent field