Previous abstract Next abstract
HUT observations of the starburst galaxies IR0833+652, Mrk1267, Mrk66, and NGC6090=Mrk496 have been obtained. All four galaxies are at a redshift of about 0.02, permitting a measurement of their intrinsic Lyman discontinuity. The HUT data longward of 912\AA\ in combination with stellar evolutionary synthesis models are used to determine the properties of the recently formed stars. Optical ground-based data are included in our discussion as well. We find evidence for a hot, ionizing stellar population at wavelengths longward of 912\AA\ in all four galaxies. However, no significant flux below 912\AA\ is detected in any of the four objects. Comparison with the extinction- corrected optical Balmer emission-line fluxes then implies that less than a few \% of the intrinsic ionizing continuum below 912\AA\ is observed by HUT (implying that starburst galaxies are rather opaque in the Lyman continuum). We discuss the implications of this result for the ionization of the intergalactic medium by galaxies with active star formation.
Tuesday program listing