We observed the Large Magellanic Cloud (LMC) in near-IR H_2 ro-vibrational lines using the University of Texas Fabry-Perot Spectrometer. The line ratios show that the UV-excited H_2 emission predominates. There is very extended H_2 emission in the 30 Doradus and N159 regions covering an area >10arcmin or 160 pc. There is H_2 emission at some positions where the SEST LMC survey failed to detect (12) CO J=1-0 emission. In models of photon dominated neutral regions at cloud boundaries, the structure of the C(+) /C/CO transition depends on the abundance and the far-UV absorption properties of the dust. Our observations, together with the SEST results imply that in some LMC clouds hydrogen is in the form of H_2 while carbon is still in ionized or neutral atomic form because of the low metallicity and high UV radiation fields. This work was supported by the David and Lucile Packard Foundation and by NSF Grant 9117373 to the University of Texas.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1995