AAS 207th Meeting, 8-12 January 2006
Session 175 Recent Discoveries in the Far UV
Poster, Thursday, 9:20am-4:00pm, January 12, 2006, Exhibit Hall

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[175.01] Ly\alpha Pumped Molecular Hydrogen Emission in the Planetary Nebulae NGC 6853 and NGC 3132

R. E. Lupu, K. France, S. R. McCandliss (Johns Hopkins University)

We report the first detection of Ly\alpha pumped molecular hydrogen emission in planetary nebulae, based on FUSE observations of NGC 6853 (905--1187~Å) and HUT observations of NGC 3132 (820--1840~Å). The atypical H2 emission observed in the spectra of NGC 6853 and NGC 3132 can be explained by excitation of vibrationally hot H2 by Ly\alpha photons. In both cases, the detected H2 lines require a temperature in the 2000 K range and a ~ 0.33 Å\ wide Ly\alpha with a deep self-reversal. These parameters satisfy both short and long wavelength constraints, pointing to similar conditions of the gas in the two nebulae. The H2 and \ion{H}{1} column densities as well as the Doppler shifts of the molecular and atomic components with respect to the nebular Ly\alpha are estimated in each case.

FUSE data were obtained under the Guest Investigator Program (NASA grant NNGO4GK82G) by the NASA-CNES-CSA FUSE mission, operated by the Johns Hopkins University.

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