The dwarf spheroidal galaxy in Draco. IV - On the mean metal abundance and metal-abundance range of the red giant stars

Abstract

view Abstract Citations (17) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The dwarf spheroidal galaxy in Draco. IV - On the mean metal abundance and metal-abundance range of the red giant stars Stetson, P. B. Abstract The spectrophotometry of Zinn (1978) and of Searle and Zinn (1978) is reexamined in order to determine whether the range of spectral properties at constant luminosities among Draco's giants is better explained by a range of initial metal abundance or by the presence of stars in different evolutionary states. Also investigated is whether Draco's giants are sufficiently similar to those in the globular clusters (GCs) such that Searle and Zinn's empirical technique for determining relative metal abundance is directly applicable. It is concluded that Draco probably differs from the clusters in some important, discrete manner; thus, secondary observational parameters which are correlated with metal abundance in normal CGs may not accurately predict the metallicity of Draco. It is also found that there is indeed a spread of temperature and spectral properties on Draco's upper giant branch, but they resemble the differences found between the first-time giant and asymptotic giant stars in GCs and do not necessarily imply a range of initial metal abundance. Publication: The Astronomical Journal Pub Date: April 1980 DOI: 10.1086/112688 Bibcode: 1980AJ.....85..398S Keywords: Abundance; Metallic Stars; Red Giant Stars; Spiral Galaxies; Stellar Spectra; Stellar Spectrophotometry; Galactic Clusters; Globular Clusters; Hertzsprung-Russell Diagram; Spectral Bands; Stellar Evolution; Stellar Luminosity; Stellar Temperature; Astrophysics full text sources ADS | data products NED (1)