ABUNDANCES IN TURNOFF STARS IN THE OLD, METAL-RICH OPEN CLUSTER, NGC 6791

Journal Article · Mon Jun 15 04:00:00 EDT 2009 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/137/6/4949; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21255718

Boesgaard, Ann Merchant ^[1]; Jensen, Elizabeth E. C. ^[2]

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1. Institute for Astronomy, University of Hawaii at Manoa, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
2. Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

Open clusters have long been used to illuminate both stellar evolution and Galactic evolution. The oldest clusters, though rather rare, can reveal the chemical and nucleosynthetic processes early in the history of the Galaxy. We have studied two turnoff stars in the old, metal-rich open cluster, NGC 6791. The Keck + HIRES spectra have a resolution of {approx}45,000 and signal-to-noise ratios of {approx}40 per pixel. We confirm the high value for [Fe/H] finding +0.30 {+-} 0.08, in agreement with earlier results from evolved stars in other parts of the Hertzsprung-Russell diagram. We have also determined abundances for Na, Si, Ca, Ti, Cr, Ni, Y, and Ba. These are compared to a sample of old, metal-rich field stars. With the probable exception of enhanced Ni in the cluster stars, the field and cluster stars show similar abundances of the elements. Model predictions show that the Ni enhancement could result from enrichment of the pre-cluster gas by SN Ia. Orbital evidence indicates that NGC 6791 could have originated near the inner regions of the Galaxy where the metallicity is generally higher than it is in the disk or halo. Subsequent perturbations and migrations may have resulted in its current heliocentric distance of 4 kpc and 1 kpc above the Galactic plane.

• OSTI ID: 21255718
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 6 Vol. 137; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
ABUNDANCE
GALACTIC EVOLUTION
GALAXIES
HERTZSPRUNG-RUSSELL DIAGRAM
PERTURBATION THEORY
SIGNAL-TO-NOISE RATIO
STAR CLUSTERS
STAR EVOLUTION
STARS