This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/70664
Description
Title
The Evolution of Planetary Nebula Nuclei
Author(s)
Shaw, Richard Allen
Issue Date
1985
Department of Study
Astronomy
Discipline
Astronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Astronomy and Astrophysics
Abstract
The evolution of planetary nebula nuclei (PNNs) is examined with the aid of the most recent available stellar evolution calculations and new observations of these objects. Their expected distribution in the log L-log T plane is calculated based upon the stellar evolutionary models of Paczynski, Schonberner and Iben, the initial mass function derived by Miller and Scalo, and various assumptions concerning mass loss during post-main sequence evolution. The distribution is found to be insensitive both to the assumed range of main-sequence progenitor mass and to reasonable variations in the age and the star forming history of the galactic disk. Rather the distribution is determined by the strong dependence of the rate of stellar evolution upon core mass, the steepness of the initial mass function, and to a lesser extent the finite lifetime of an observable planetary nebula. The theoretical distributions are rather different than any of those inferred from earlier observations. Possible observational selection effects that may be responsible are examined, as well as the intrinsic uncertainties associated with the theoretical model predictions.
An extensive photometric and smaller photographic survey of southern hemisphere planetary nebulae (PNs) is presented. Seven new PNs were discovered in or near Baade's Window, and total fluxes in several nebular lines, relative to H(beta), are presented for 134 southern PNs. New B and/or V magnitudes for the nuclei of 117 PNs are presented, and are combined with 54 magnitudes (as well as limits for ten others) from absolute photometry of northern PNNs. We develop a superior method of extracting stellar continuum fluxes from a bright nebular background, and carefully examine the errors and limitations of the method.
The continuum measurements are compared with the widely circulated list of preliminary central star magnitudes by Shao and Liller, which are shown to suffer frequently from severe contamination from the nebular continuum. A calibration for older photographic magnitudes is determined, and the effect of the nebular contamination of the stellar continuum for luminous objects on the study of the evolution of PNNs is examined.
The temperatures and luminosities are derived for nearly all of the PNNs in this sample via the Zanstra and Shklovsky methods. The observed log L-log T distribution of PNNs is presented, and large discrepancies with the theoretical distributions are examined. In particular, the Zanstra technique is found to be unable to yield stellar temperatures much hotter than log T (TURN) 5.1. This limitation and the effects of stellar winds and an uncertain distance scale upon the study of PNN evolution are evaluated and discussed.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
