\omega Cen contains the largest population of very hot horizontal branch ( HB ) stars known in a globular cluster .
Recent UV observations ( Whitney et al . [ 1998 ] ; D ’ Cruz et al . [ 2000 ] ) show a significant population of hot stars below the zero-age horizontal branch ( “ blue hook ” stars ) , which can not be explained by canonical stellar evolution .
Stars which suffer unusually large mass loss on the red giant branch and thus experience the helium core flash while descending the white dwarf cooling curve could populate this region .
Theory predicts that these “ late hot flashers ” should show higher temperatures than the hottest canonical HB stars and should have helium- and carbon-rich atmospheres .
We obtained and analysed medium resolution spectra of a sample of blue hook stars to derive their atmospheric parameters .
The blue hook stars are indeed both hotter ( { T _ { eff } } \geq 35,000 K ) and more helium-rich than classical extreme HB stars .
In addition we find indications for a large enhancement of the carbon abundance relative to the cluster abundance .