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

Abstract

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