Identification of Emission-Line Stars in 30 Doradus using HST Observations
Session 31 -- Massive Hot Stars
Display presentation, Tuesday, 31, 1994, 9:20-6:30

## [31.03] Identification of Emission-Line Stars in 30 Doradus using HST Observations

Joel Wm. Parker (GSFC / NRC), Sara R. Heap (GSFC / NASA)

Using F469N narrow-band (Campbell et al.\/ 1992, ApJ, 104, 1721) and F439W broad-band (Malumuth \& Heap 1994, ApJ, 107, 1054) HST\/ archive images of the R\,136 central cluster of 30 Doradus, we have identified Wolf-Rayet and Of stars from the strength of their He\,{\sc ii}~$\lambda4686$ emission lines. Fluxes are calculated in both filters for over 700 stars in R\,136 and the surrounding region. We have determined photometric equivalent widths'' from these fluxes, and compare these results with spectroscopically determined equivalent widths. We show how observations such as these can be used to study the massive star content and age of other star-formation regions. We also compare the ratio of Wolf-Rayet to O stars found in our data with the ratio determined from evolutionary model predictions for low-metallicity galaxies (Maeder 1990, A\&AS, 84, 139; Maeder 1991, A\&A, 242, 93; Schaerer et al.\/ 1993, A\&AS, 98, 523).