Advanced evolution in globular clusters. II - The ultraviolet-bright stars in omega Centauri

Abstract

view Abstract Citations (41) References (61) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Advanced evolution in globular clusters. II. The ultraviolet-bright stars in Omega Centauri. Norris, J. Abstract The results of a spectrographic and photometric survey of stars which occupy the region above the horizontal branch and to the left of the giant branch (the so-called UV-bright region) in the color-magnitude diagram of the globular cluster omega Centauri are presented. There is no large scatter in the apparent metal abundances of the cool stars ROA 164 and 342 and the red giant ROA 159. Helium lines are present in the spectra of ROA 3596 and 5701. A mean mass of about 0.58 solar mass (internal s.e.) is obtained for the UV-bright stars, indicating that they have the same mass as the blue horizontal-branch stars. The distribution of the UV-bright stars in the theoretical H-R diagram indicates that these objects can occupy any position in the UV-bright region. This implies that if they are to be explained by loops resulting from helium shell flashes and/or by final evolution from the asymptotic branch or the giant branch, the loops must be long and occur at a range in luminosities, and/or the final evolution from the giant branches must occur at a range of luminosities. Publication: The Astrophysical Journal Pub Date: November 1974 DOI: 10.1086/153228 Bibcode: 1974ApJ...194..109N Keywords: Abundance; Globular Clusters; Radial Velocity; Stellar Evolution; Stellar Spectrophotometry; Ultraviolet Spectra; Color-Magnitude Diagram; Cool Stars; Galactic Evolution; Giant Stars; Hubble Diagram; Milky Way Galaxy; Stellar Atmospheres; Stellar Luminosity; Stellar Mass; Ubv Spectra; Astronomy full text sources ADS | data products SIMBAD (37)