Previous abstract Next abstract

Session 42 - Molecular Clouds: Models and Observations.
Display session, Tuesday, June 11
Great Hall,

[42.12] Ionized Helium in Low Surface Brightness HII Regions

D. S. Balser, F. J. Lockman (NRAO)

We have observed H and He radio recombination line emission in several low surface brightness HII regions to estimate the hardness of the ionizing radiation. Radio continuum observations of HII regions provide information about the total number of H ionizing photons. Measurements of He+/H+ in these regions constrain the initial mass function and thus the hardness of the stellar radiation field. Diffuse HII regions are not as well studied as a class of objects throughout the Galactic plane as classical HII regions, such as Orion, but may contribute significantly to the global ionization of gas in the Galaxy. Moreover, they may be an important source of ionizing photons for the extended low density warm ionized medium (ELDWIM) if they are density bounded.

Program listing for Tuesday