Structure and Evolution of Hot Gas in 30 Dor

We have investigated the structure and evolution of hot gas in the 30 Dornebula, based on recent X-ray observations. Our deep ROSAT HRI image shows thatdiffuse X-ray emission arises in blister-shaped regions outlined by loops ofHII gas. X-ray spectroscopic data from ASCA confirm the thermal nature of theemission and indicate that hot gas temperature decreases from the core to thehalo of the nebula. The structure of the nebula can be understood as outflowsof hot and HII gases from the parent giant molecular cloud of the central OBassociation. The dynamic mixing between the two gas phases is likelyresponsible for the mass loading to the hot gas, as required to explain theobserved thermal structure and X-ray luminosity of the nebula. Such processesshould also be important in the formation of similar giant HII regions and intheir subsequent evolution into supergiant bubbles or galactic chimneys.Comment: 9 page text plus 4 color figures. To appear in ApJ