KINEMATICS AND ELECTRON TEMPERATURES IN THE CORE OF ORION-A

A map of the core of Orion A, with a 42 '' resolution in the 64 alpha recombination line of hydrogen, covering similar to 5' by similar to 5 ' is presented. The V-lsr distribution shows a complex variation about the center of the ionized gas emission: From Delta alpha=-200 '' to 300 '', the V-lsr varies from -5km s(-1) to +2km s(-1) then to -4km s( -1), finally rising to +3km s(-1). A search for cold (T-e similar to 3 000K) ionized gas toward the KL nebula has revealed no measurable diff erences in T-e between this region and other parts of Orion A. The ave rage T-e from our data is 8300+/-200K. We find no significant differen ce between T-e values determined from radio recombination lines and th ose determined from forbidden optical lines of [OIII], although the T- e value from Balmer decrement data is markedly lower. The turbulent ve locity varies by <5% over the region mapped. On the basis of our 2.45' resolution, high dynamic range 6 cm continuum map, we find that the e mission falls off faster in the East than in the West. We find support for the model in which Orion A is ionization bounded in the East but density bounded in the West. The ionized gas in the West is flowing in the direction of the Sun, while the more positive V-lsr values in the east may be caused by the flow of ionized gas off the foreground Dark Bay. This ionized region may have little fine scale structure, since there is little continuum emission in interferometer maps.