A SEARCH FOR FIELD HORIZONTAL-BRANCH STARS NEAR THE SOUTH GALACTIC POLE
- Escola de Artes, Ciencias e Humanidades, USP, Av. Arlindo Bettio, 1000, 03828-000, Sao Paulo, SP (Brazil)
- Department of Physics, Campus Box 41051, Texas Tech University, Lubbock, TX 79409 (United States)
- Departamento de Astronomia, IAG/USP, Rua do Matao, 1226, Cidade Universitaria, 05508-900, Sao Paulo, SP (Brazil)
Searches for field horizontal-branch (FHB) stars in the halo of the Galaxy in the past have been carried out by several techniques, such as objective-prism surveys and visual or infrared photometric surveys. By choosing adequate color criteria, it is possible to improve the efficiency of identifying bona fide FHB stars among the other objects that exhibit similar characteristics, such as main-sequence A-stars, blue stragglers, subdwarfs, etc. In this work, we report the results of a spectroscopic survey carried out near the south Galactic pole intended to validate FHB stars originally selected from the HK objective-prism survey of Beers and colleagues, based on near-infrared color indices. A comparison between the stellar spectra obtained in this survey with theoretical stellar atmosphere models allows us to determine T {sub eff}, log g, and [Fe/H] for 13 stars in the sample. Stellar temperatures were calculated from measured (B - V) {sub o}, when this measurement was available (16 stars). The color index criteria adopted in this work are shown to correctly classify 30% of the sample as FHB, 25% as non-FHB (main-sequence stars and subdwarfes), whereas 40% could not be distinguished between FHB and main-sequence stars. We compare the efficacy of different color criteria in the literature intended to select FHB stars, and discuss the use of the Mg II 4481 line to estimate the metallicity.
- OSTI ID:
- 21301264
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 139, Issue 3; Other Information: DOI: 10.1088/0004-6256/139/3/1031; Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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