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Title:The Physical Nature of The Symbiotic Stars
Author(s):Kenyon, Scott Jay
Department / Program:Astronomy
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Physics, Astronomy and Astrophysics
Abstract:The physical nature of the peculiar emission-line objects known as symbiotic stars is examined. The available observations of these objects can be understood best if they are binaries consisting of a late-type giant and a hot component which ionizes a gaseous nebula.
New 2-4 micron low resolution spectra of symbiotic stars are compared to spectra of normal M-type giants and supergiants. The 14 symbiotics observed in this study have the strong CO absorption band at 2.29 microns that is characteristic of M-type giants and supergiants. CI Cyg, T CrB and Z And have CO bands which are comparable in strength to some M-type supergiants and bright giants, suggesting these systems contain very evolved stars on the asymptotic giant branch. The remaining systems have CO bands resembling those observed in normal M-type giants.
New optical spectrophotometric observations show long-term variability in Z And, CI Cyg and AX Per which appear to be eclipses. An analysis of the strong H I, He I and He II emission lines implies effective temperatures of 100,000 K and luminosities of 1000 L(,(CIRCLE)) are appropriate for most symbiotic hot components. The {O III} and {Fe VII} line intensities require low density nebulae in some symbiotics (log n = 6; e.g. V1016 Cyg) and high density nebulae in others (log n = 9; e.g. CI Cyg).
Spectrum synthesis techniques have been used to determine the physical nature of symbiotic hot components. The UV continua of many symbiotics (e.g. CI Cyg and AX Per) are produced in an accretion disk surrounding a low mass main sequence star. These binaries may evolve into cataclysmic variables. Most other systems (e.g. EG And and V443 Her) appear to be hot stellar sources with effective temperatures of 25-100,000 K. Such binaries probably evolve into planetary nebulae with double white dwarf nuclei.
Issue Date:1983
Description:357 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
Other Identifier(s):(UMI)AAI8409968
Date Available in IDEALS:2014-12-16
Date Deposited:1983

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