Paul T. P. Ho

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.

Ammonia Observations of Dark Clouds Containing Herbig-Haro Objects

A study in NH 3 was conducted towards H-H objects. Cloud fragmentation appears to have occurred in the regions mapped. Rotation is present with velocity gradients of 1-2 km s −1 pc −1 . We suggest that in the regions containing H-H objects, formation of stars of different spectral types may be taking place.