The 30 Doradus nebula. I. Spectral classification of 69 stars in the central cluster.

Spectral types are given for 69 stars in and near the ionizing cluster of the 30 Doradus nebula. Out of the 60 stars classified within 25 pc of the cluster center, 49 are O stars, 12 are WR stars, 8 are B-supergiants, and one is an M-supergiant. At least 15 of the O stars have spectral types earlier than O6 and six have O3 types. These numbers, however, are somewhat uncertain because the spectral classification of early O stars in 30 Dor is difficult because of contamination by nebular lines. The combined ionizing fluxes of the stars classified spectroscopically excluding R136a account for more than one half of the Lyman continuum photons required to explain the ionization of the 30 Doradus nebula. The present observations argue strongly against the existence of a supermassive object in the core of the cluster (R 136).