Variations in C-12/C-13 as an explanation for the 3883 A CN-bimodality among 47 Tucanae subgiants

Abstract

view Abstract Citations (21) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Variations in 12C/ 13C as an Explanation for the 3883 Angstrom CN-Bimodality among 47 Tucanae Subgiants Briley, Michael M. ; Bell, Roger A. ; Smith, Graeme H. ; Hesser, James E. Abstract Spectroscopic observations of subgiants in the metal-rich globular cluster 47 Tucanae are used to measure the strengths of the CN bands located at 3883 A and 4215 A. A bimodal distribution is clearly seen in the 3883 A CN band strengths, but not in the 4215 A bands. Synthetic spectrum calculations are used to probe the effect on both CN bands of varying the C-12/C-13 ratio. The sensitivity of the 3883 A CN feature to C-13 relative abundance is found to be considerably higher than that of the 4215 A band for the stars observed. Thus, spectroscopic indices derived from these features are observable probes of atmospheric C-13/C-12 enhancements. It is suggested that the bimodality observed in the 3883 A CN band may be due largely to a difference in the C-12/C-13 ratios of the two groups. Publication: The Astrophysical Journal Pub Date: June 1989 DOI: 10.1086/167537 Bibcode: 1989ApJ...341..800B Keywords: Abundance; Astronomical Spectroscopy; Cn Emission; Globular Clusters; Subgiant Stars; Carbon 12; Carbon 13; Metallicity; Stellar Spectra; Stellar Structure; Astrophysics; CLUSTERS: GLOBULAR; STARS: ABUNDANCES full text sources ADS | data products SIMBAD (2)