Chemical abundances in the globular clusters M3, M13, and NGC 6752

Journal Article · Mon Dec 01 04:00:00 EST 1980 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/158502· OSTI ID:6791155

Bell, R A; Dickens, R J

The abundances of iron, carbon, nitrogen, and oxygen have been investigated in red giant stars in the globular clusters M3, M13, and NGC 6752. The results are based on application of spectrum synthesis and theoretical colors to observed spectra, DDO colors, and infrared CO measurements. Carbon is depleted by a factor of about 3 relative to other metals in most giants studied, with no evidence for the discontinuity along the giant branch at M/sub v/approx. =-0.7 found for more metal-poor clusters. This contrasts with the greater depletion of about a factor of 6 for the more metal-poor cluster stars, a difference which is expected if meridional mixing is responsible for the carbon depletion. The spectroscopic results for nitrogen are imprecise, but the colors suggest enhancements of a factor of 3. The iron abundances for M3 and M13 stars have been determined from published equivalent widths, yielding (Fe/H) close to -1.4 for both clusters. The uncertainties in M3 and M13 CO colors and (O I) equivalent widths make it impossible to derive accurate oxygen abundances, but the depletion of carbon is real and is not caused by an overabundance of oxygen.

• Research Organization: Astronomy Program, University of Maryland
• OSTI ID: 6791155
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 242:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
CARBON
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL COMPOSITION
DIAGRAMS
ELEMENTS
ENERGY SPECTRA
GIANT STARS
IRON
METALS
NITROGEN
NONMETALS
OPTICAL DEPTH CURVE
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHOTOMETRY
RED GIANT STARS
SPECTRA
SPECTROSCOPIC CURVE OF GROWTH
STAR CLUSTERS
STARS
TRANSITION ELEMENTS