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Session 46 - Interstellar Scattering and Scintillation as Tools in Radio Astronomy.
Topical, Oral session, Tuesday, June 09
Sierra/Padre,
For DM > 200 cm^-3 pc more scattering is seen from pulsars than would be expected by extrapolating from lower DMs. Lockman, Pisano amp; Howard (Ap.J. 472, 173, 1996) identified 130 "diffuse" H II regions in the inner galaxy. These diffuse H II regions have similar properties to those of the Rosette Nebula if it were placed near the Galactic Center. The Rosette Nebula has DM \sim 300 cm^-3 pc suggesting that diffuse H II regions could be responsible for the enhanced scattering of pulsars seen towards the galactic center. Comparisions of the observed scattering parameters of pulsars with their angular distance from the nearest diffuse H II region suggests that the known diffuse H II regions could be responsible for the enhanced scattering.