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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 thezero-age horizontal branch (``blue hook'' stars), which cannot be explained bycanonical stellar evolution. Stars which suffer unusually large mass loss onthe red giant branch and thus experience the helium core flash while descendingthe white dwarf cooling curve could populate this region. Theory predicts thatthese ``late hot flashers'' should show higher temperatures than the hottestcanonical HB stars and should have helium- and carbon-rich atmospheres. Weobtained and analysed medium resolution spectra of a sample of blue hook starsto derive their atmospheric parameters. The blue hook stars are indeed bothhotter (Teff > 35,000K) and more helium-rich than classical extreme HB stars.In addition we find indications for a large enhancement of the carbon abundancerelative to the cluster abundance.Comment: 8 pages, 5 figures, uses aa.cls (included), accepted for publication  in A&

Spectroscopic analyses of the “blue hook” stars inωCentauri: A test of the late hot flasher scenario