J. L. Turner

Brackett line spectroscopy of bursts of star formation in the nuclei of galaxies

Br-alpha and Br-gamma lines with 7.2 arcsec spatial and 350 km/s spectral resolution have been observed in seven infrared-bright galaxies, and the measurements are used to derive the Lyman continuum flux and the luminosity resulting from young stars. By analyzing the possible range of uncertainties in various parameters of the derivations, it is shown that several of the galaxies appear to have quite extreme conditions, with OB populations that are probably more massive and, in some cases, much younger than seen locally. 65 refs.

Gas and hidden star formation in NGC 5253

We confirm the presence of compact H II regions in the center of the starburst in NGC 5253 through the detection of optically thick free-free emission. The number of O-type stars implied by the excitation of these nebulae is nearly two orders of magnitude larger than what is indicated by the radio continuum fluxes. The compact H II regions are located 70 pc to the north of the location of the Wolf-Rayet feature. Implied extinctions are extremely high. Not all WR galaxies can be identified as such due to extinction.