Detection of Wolf-Rayet Stars of WN and WC Subtypes in SuperStar Clusters of NGC 5253

摘要

We present spectroscopic observations of the central star clusters in NGC 5253, the aim of which is to search for WC stars. Our observations show the presence of Wolf-Rayet (W-R) stars not only of WN but also of WC subtype in two star-forming regions corresponding to the maximum optical and UV emission. The massive star population that we derive is consistent with young bursts of ～3 and ～4 Myr. The region of maximum optical emission is found to provide the dominant contribution to the ionizing flux, as opposed to the less extinguished region of maximum UV brightness. The presence of W-R stars near the N-enriched regions found by Walsh & Roy and Kobulnicky et al. suggests that they are a possible source of nitrogen. It is presently unclear whether our detection of WC stars is compatible with the normal observed He/O and C/O abundance ratios.