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Session 80 - Central Stars of Planetary Nebulae.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center

[80.08] Spectral Characteristics and Physical Parameters of Central Stars of Planetary Nebulae via NLTE Modeling

M. F. Quigley, F. C. Bruhweiler (Catholic U.)

Central stars of planetary nebulae (CSPN) typically have T_eff in excess of 30,000K, thus radiating primarily in the UV, while also exhibiting strong non-local thermal equilibrium effects. Previous efforts at NLTE modeling of CSPN have been directed towards synthesizing individual H and He absorption features in the optical or near UV regions, using model atmospheres composed of pure H and He.

We present synthetic spectra of extended spectral regions composed mainly of Fe and Ni lines in the range 1250-1650 Åfor six CSPN, employing the hybrid CL/ALI NLTE code recently developed by Hubeny and Lanz, with model atmospheres composed of H, He, CNO, and Fe. Mass loss and nebular contamination result in CNO features which for the most part are not reproducible. However, broad sections of the spectrum composed mainly of Fe V, Fe VI, Ni V, and Ni VI photospheric lines are closely replicated.

Effective temperatures of the six CSPN in our study (IC 418, IC 4593, NGC 2392, IC 2149, NGC 6543, and NGC 6826), range from 36,000K (IC 418) to 50,000K (NGC 6826). Abundances for all these stars are roughly solar, with C and O somewhat enriched.

Program listing for Wednesday