Spectroscopic studies of O-type stars. III. The effective-temperature scale.

An effective-temperature scale for 0-type stars is presented, based upon a comparison of measures of A4471 He 1lA454l He ii and predictions from the non-LTE models of Auer and Mihalas. There is reasonably good agreement between this scale and the effective temperatures inferred from O stars in H ii regions by the Zanstra method. The problems associated with the low effective temperature derived for Pup by interferometric methods are also discussed. Subject headings: atmospheres, stellar - early-type stars - emission-line stars - Of stars