NGC 604 - A giant H II region dominated by many WR stars

NGC 604, the largest H II region in M 33, is comparable in many respects (eg. ionized mass, total extent of a few hundred pc) with the giant H II complex 30 Doradus of the LMC. Recently D'Odorico and Rosa (1981) discovered broad WR emission features at 4640 A, 4660 A, He II 4686 A and 5812 A in a number of the bright knots in the core of NGC 604. In that paper it was concluded, that about 50 WR stars, mainly of the transition type WN 7 but WC characteristics seen as well, are present in the H II region. These findings were confirmed by the observations by Conti and Massey (1981) and are briefly discussed here. The WR stars in NGC 604 appear to dominate the kinetic energy balance and the formation of large scale structures in this particular giant H II region. (Auth.)