The stellar population in the Wolf-Rayet knot in NGC 5430.

Abstract

The barred spiral NGC 5430 contains an extremely luminous H II region showing very strong He II and N III Wolf-Rayet (WR) emission features. Spectrophotometry from 1200 - 7000 Å has been obtained. From these data, limits on the reddening and effective temperature of the stellar population are derived; T_eff is between 25000 and 35000K. No UV emission lines are clearly detected. The Hα linewidth implies a very short timescale for star formation here, less than 10⁷yr for ≡5×10⁵ OB and WR stars. Hα photometry shows a population of normal H II regions below 3% of the flux of the giant WR complex. The two most luminous of these are closest to the WR knot; the rest appear to have a normal Hα luminosity function.