UV Observations of the SMC

The FUV photometry is compared with available ground-based catalogs of supergiants, yielding 191 detections of 195 supergiants with spectral type earlier than F0 in the UIT fields. The (m(162)-V) color for supergiants is a sensitive measure of spectral type. The bluest observed colors for each type agree well with colors computed from unreddened Galactic spectral atlas stars for types earlier than about A0; for later spectral types the observed SMC stars range significantly bluer, as predicted by comparison of low-metallicity and Galactic-composition models.

Redder colors for some stars of all spectral types are attributed to the strong FUV extinction arising from even small amounts of SMC dust. Internal SMC reddenings are determined for all catalog stars. All stars with E(B-V)>0.15 are within regions of visible H{alpha} emission.

FUV photometry for 42 H{alpha} -selected H II regions in the SMC Bar is obtained for stars and for total emission (as measured in H II-region-sized apertures). The flux-weighted average ratio of total to stellar FUV flux is 2.15; consideration of the stellar FUV luminosity function indicates that most of the excess total flux is due to scattered FUV radiation, rather than stars fainter than m(162)=14.5. Both stellar and total emission are well correlated with H{alpha} fluxes measured by Kennicutt and Hodge (1986ApJ...306..130K), yielding FUV/H{alpha} flux ratios that are consistent with models of SMC metallicity, ages from 1-5Myr, and moderate (E(B-V)=0.0-0.1mag) internal SMC extinction.

(Copyright) 1997 American Astronomical Society.