A multi-frequency study of symbiotic stars
type: CreativeWork
description: Multi-frequency observations using a wide variety of telescopes and instrumentation have been used to throw light upon some of the physical characteristics of symbiotic stars. A detailed understanding of these enigmatic binaries requires the planning of large, simultaneous observing campaigns to obtain the maximum possible range of diagnostic tools - line ratios, profiles and intensities and continuum flux densities. This then is the general theme of the work presented in this thesis. The results of a low dispersion, optical spectroscopic survey of northern sky symbiotics are presented and reference is made to the high dispersion counterpart. Preliminary analysis has diagnosed that the dominant excitation mechanism operating in several symbiotic binaries is radiative. Simultaneous optical/ultraviolet and optical/infrared observations of AX Persei and CH Cygni, respectively, are discussed. For AX Per, a simple model is proposed. This explains the observed line profiles, the variability of optical and ultraviolet line ratios and the recent V-band light curve in terms of the gradual obscuration of the outbursting primary component by the large, dusty envelope of the late-type secondary. Light curves have been used to estimate both the distance to the system and the physical extent of the emission regions. Revised positional coordinates are also given. For CII C yg , optical/infrared spectroscopy has been used to classify the cool secondary star. Near-simultaneous optical and radio observations of a sample of symbiotic stars have been used to demonstrate an apparent division between D- and S-type symbiotics. The use of Baimer line ratios as a primary indicator of interstellar extinction has been investigated and rejected. Estimates of 5-GHz optical depth, turnover frequency, angular diameter and mass-loss rate are calculated and an extinction-based method of distance determination is discussed. The ionized regions of D-type syrnbiotics have been shown to be more extensi…
abstract: Multi-frequency observations using a wide variety of telescopes and instrumentation have been used to throw light upon some of the physical characteristics of symbiotic stars. A detailed understanding of these enigmatic binaries requires the planning of large, simultaneous observing campaigns to obtain the maximum possible range of diagnostic tools - line ratios, profiles and intensities and continuum flux densities. This then is the general theme of the work presented in this thesis. The results of a low dispersion, optical spectroscopic survey of northern sky symbiotics are presented and reference is made to the high dispersion counterpart. Preliminary analysis has diagnosed that the dominant excitation mechanism operating in several symbiotic binaries is radiative. Simultaneous optical/ultraviolet and optical/infrared observations of AX Persei and CH Cygni, respectively, are discussed. For AX Per, a simple model is proposed. This explains the observed line profiles, the variability of optical and ultraviolet line ratios and the recent V-band light curve in terms of the gradual obscuration of the outbursting primary component by the large, dusty envelope of the late-type secondary. Light curves have been used to estimate both the distance to the system and the physical extent of the emission regions. Revised positional coordinates are also given. For CII C yg , optical/infrared spectroscopy has been used to classify the cool secondary star. Near-simultaneous optical and radio observations of a sample of symbiotic stars have been used to demonstrate an apparent division between D- and S-type symbiotics. The use of Baimer line ratios as a primary indicator of interstellar extinction has been investigated and rejected. Estimates of 5-GHz optical depth, turnover frequency, angular diameter and mass-loss rate are calculated and an extinction-based method of distance determination is discussed. The ionized regions of D-type syrnbiotics have been shown to be more extensi…
author: Ivison, Robert Julian
language: en
keywords: F500 - Astronomy
date published: 1992-02
date modified: 2026-07-24T01:36:16Z
provider: University of Central Lancashire
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Lancashire Polytechnic