High Resolution IR Observations of W28A2
Session 34 -- Airbourne Astronomy
Display presentation, Tuesday, 9:30-6:30, Pauley Room

## [34.14] High Resolution IR Observations of W28A2

P.M.Harvey, C.Colome, D.F.Lester, B.J.Smith (UTexas)

W28A2 (G05.89-0.2) is a very compact H II region associated with an extremely energetic bipolar outflow. High angular resolution far-ir observations from NASA's KAO reported by Lester et al. (1987; BAAS, 19, 1016) showed that the dust around this H II region is optically thick in the far-ir. We have re-observed W28A2 with a new, high resolution far-ir radiometer on the KAO as well as obtained 1 -- 4$\mu$m imaging at NASA's IRTF. The far-ir data confirm the fact that the 50 and 100$\mu$m emission is unresolved and optically thick. The near-ir imaging reveals a bipolar structure, possibly reflection nebulosity, at the shorter wavelengths, and a compact source at 3.8$\mu$m with a morphology much like that seen at 10$\mu$m. Radiative transfer modeling of the source shows that a relatively steep dust density gradient is required, $\rho \propto r^{-n}$, with n $\sim$ 3 -- 5. The near-ir morphology is consistent with the presence of a dense disk, suggested also by the existence of a strong bipolar outflow.