Spectral Energy Distributions of starburst galaxies in the 900-1200 Å range

Abstract

We present the 970-1175 Å spectral energy distributions (SEDs) of 12 starburst galaxies observed with the Far Ultraviolet Spectroscopic Explorer FUSE. We benefit from the high spectral resolution of FUSE to estimate a continuum as much as possible unaffected by the interstellar lines. The continuum is rather flat with, in a few cases, a decrease at lambda < 1050 Å, the amplitude of which is correlated with various indicators of dust extinction. The far-UV SEDs are compared with synthetic population models. The galaxies with almost no extinction have an SED consistent with on-going star formation over some Myrs. We derive a mean dust attenuation law in the wavelength range 965-1140 Å by comparing the SED of obscured galaxies to an empirical dust-free SED. The extinction is nearly constant longward of 1040 Å but rises at shorter wavelengths. We compare our results with other studies of extinction for galaxies and stars in this wavelength range.