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Session 97 - Planetary Nebulae.
Display session, Thursday, January 16
Metropolitan Ballroom,

[97.14] The Abundance of ^3He and Evidence for a Large Halo in the Planetary Nebulae NGC3242

D. S. Balser (NRAO), T. M. Bania (Boston U.), R. T. Rood (U. Virginia), T. L. Wilson (MPIfR)

Observations of the hyperfine ^3He^+ line and radio recombination lines of H and ^4He at 8.7 GHz indicate the presence of a low surface brightness, extended halo surrounding the planetary nebula NGC3242. Numerical models are developed to produce synthetic spectra for an ionized nebula which predict such a halo for NGC3242. We determine a ^3He^+/H^+ abundance ratio of 0.6 \pm 0.1 \times 10^-3, which is consistent with the expected enrichment of ^3He predicted by standard stellar models of low-mass stars. We conclude that the ionized halo is associated with the planetary nebula.

Program listing for Thursday