### Session P1: Posters and Coffee Break

3:30 PM–3:30 PM, Friday, October 6, 2006
UT Arlington, University Center Room: Rio Grande, 3:30pm-5:30pm

Chair: Robert Ramsey, Pete Williams, Marcus Hawkins, Heather Brown, University of Texas at Arlington

Abstract ID: BAPS.2006.TSF.P1.3

### Abstract: P1.00003 : Spectroscopic Study of Nuclear Processing in the Crab Nebula

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#### Authors:

Gordon MacAlpine
Tait Ecklund
William Lester
Steven Vanderveer
(Trinity University)

We present correlations for optical and near-infrared line intensity measurements at many positions in the Crab Nebula supernova remnant. These correlations suggest the existence of gas produced by a range of nuclear processing, from material in which synthesis ended with the CNO-cycle, to some helium-burning and nitrogen depletion, to regions containing enriched products of oxygen-burning. The latter exhibit a gradual, linear rise of [Ni II] emission with increasing argon enrichment, whereas gas with less nuclear processing shows markedly different [Ni II] emission characteristics, including the highest derived abundances. This suggests two origins for stable, neutron-rich nickel in the nebula: a type of alpha-rich freezeout'' in the most highly processed material, and perhaps removal of ions from the neutron star in other regions. In addition, the data indicate that anomalously strong observed [C I] emission comes from extensive, warm, low-ionization zones. Although the strongest He I emission could also be enhanced in similar low-ionization gas, correlations between relevant line ratios argue against that explanation, strengthening the case for an exceptionally high helium mass fraction in some locations.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2006.TSF.P1.3