Metal Absorption Profiles from the Central Star of the Planetary Nebula M27 (NGC 6853, PN G060.8-03.6, the Dumbbell) -- Photospheric and Nebular Line Identifications

摘要

High resolution spectra of the hot central star of the planetary nebula(CSPN) M27, acquired with the Far Ultraviolet Spectroscopic Explorer (FUSE),have revealed an unusually rich set of narrow molecular hydrogen absorptionfeatures. This object is also unique in that the velocity of nebular absorptionfeatures are cleanly separated from the velocity of the interveninginterstellar medium. These features blend with and in many cases obscure atomicfeatures. We have developed a continuum model of the CSPN including atomic andmolecular hydrogen absorption. Using this model we have identified andtabulated the metal lines as arising from either photospheric, nebular and/ornon-nebular velocity systems. We find the nebular outflow and ionizationbalance to be stratified with high ionization states favored at low velocityand low ionization states favored at high velocity. Neutrals and molecules arefound at a velocity that marks the transistion between these two regimes. Theseobservations are a challenge to the interacting wind model of PN evolution.Mappings at high resolution of the line profiles for ion{C}{1} ion{-}{4},ion{N}{1} ion{-}{3}, ion{O}{1}, ion{O}{6}, ion{Si}{2} ion{-}{4},ion{P}{2} ion{-}{5}, ion{S}{2} ion{-}{4}, ion{Ar}{1} ion{-}{2} andion{Fe}{2} ion{-}{3} within the FUSE and STIS bandpasses are presented. Thedigitial spectra of the stars and the model are freely available on theH$_2$ools website. They will be useful for photospheric analyses seeking todetermine the metallicity of the central star and for absorption line basedatomic and molecular abundance determination of the nebular outflow.