期刊
ASTROPHYSICAL JOURNAL
卷 701, 期 2, 页码 1323-1335出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/701/2/1323
关键词
galaxies: dwarf; galaxies: individual (Fornax); globular clusters: individual (Fornax 5); stars: horizontal-branch; stars: variables: other; techniques: photometric
资金
- PRIN INAF
- Proyecto Basal [PFB-06/2007]
- FONDAPCentro de Astrof isica [15010003]
- Proyecto FONDECYT [1071002]
- John Simon Guggenheim Memorial Foundation Fellowship
- National Science Foundation [0607249]
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [0607249] Funding Source: National Science Foundation
We present a new study of the variable star population in globular cluster 5 of the Fornax dSph, based on B and V time series photometry obtained with the MagIC camera of the 6.5 m Magellan Clay telescope and complementary Hubble Space Telescope archive data. Light curves and accurate periodicities were obtained for 30 RR Lyrae stars and one SX Phoenicis variable. The RR Lyrae sample includes 15 fundamental-mode pulsators, 13 first-overtone pulsators, one candidate double-mode pulsator and one RR Lyrae star with uncertain type classification. The average and minimum periods of the ab-type RR Lyrae stars, < P-ab > = 0.590 days, P-ab,(min) = 0.53297 days and the position in the horizontal branch type-metallicity plane, indicate that the cluster has Oosterhoff-intermediate properties, basically confirming previous indications by Mackey & Gilmore, although with some differences both in the period and type classification of individual variables. The average apparent magnitude of the Fornax 5 RR Lyrae stars is < V(RR)> = 21.35 +/- 0.02 mag (sigma = 0.07 mag, average on 14 stars more likely belonging to the cluster, and having well sampled light curves). This value leads to a true distance modulus of mu(0) = 20.76 +/- 0.07 (d = 141.9(-4.5)(+4.6) kpc) if we adopt for the cluster the metal abundance by Buonanno et al. ([Fe/H]= -2.20 +/- 0.20), or mu(0) = 20.66 +/- 0.07 (d = 135.5(-4.3)(+4.4) kpc), if we adopt Strader et al.'s metal abundance ([Fe/H]= -1.73 +/- 0.13).
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