THE CHEMICAL COMPOSITION OF RED GIANT BRANCH STARS IN THE GALACTIC GLOBULAR CLUSTERS NGC 6342 AND NGC 6366
- Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, MS-15, Cambridge, MA 02138 (United States)
- Department of Physics and Astronomy, UCLA, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547 (United States)
- Astronomy Department, Indiana University Bloomington, Swain West 319, 727 East 3rd Street, Bloomington, IN 47405-7105 (United States)
- UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)
We present radial velocities and chemical abundances for red giant branch stars in the Galactic bulge globular clusters NGC 6342 and NGC 6366. The velocities and abundances are based on measurements of high-resolution ( R ≳ 20,000) spectra obtained with the MMT–Hectochelle and WIYN–Hydra spectrographs. We find that NGC 6342 has a heliocentric radial velocity of +112.5 km s{sup −1} ( σ = 8.6 km s{sup −1}), NGC 6366 has a heliocentric radial velocity of −122.3 km s{sup −1} ( σ = 1.5 km s{sup −1}), and both clusters have nearly identical metallicities ([Fe/H] ≈ −0.55). NGC 6366 shows evidence of a moderately extended O–Na anti-correlation, but more data are needed for NGC 6342 to determine if this cluster also exhibits the typical O–Na relation likely found in all other Galactic globular clusters. The two clusters are distinguished from similar metallicity field stars as having larger [Na/Fe] spreads and enhanced [La/Fe] ratios, but we find that NGC 6342 and NGC 6366 display α and Fe-peak element abundance patterns that are typical of other metal-rich ([Fe/H] > −1) inner Galaxy clusters. However, the median [La/Fe] abundance may vary from cluster-to-cluster.
- OSTI ID:
- 22662999
- Journal Information:
- Astronomical Journal (Online), Journal Name: Astronomical Journal (Online) Journal Issue: 1 Vol. 152; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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