Using observations of detached double degenerate binaries to test theories of stellar evolution in close binary systems
Using observations of detached double degenerate binaries to test theories of stellar evolution in close binary systems
The work presented in this thesis is a study of how observational measurements of detached double degenerate (DD) binaries can be used to test our understanding of the evolution of close binary stars. Where close binary stars are defined as those which will interact via mass transfer as the stars evolve off the main-sequence.
The introduction describes the physical processes leading to the formation of both single and binary white dwarfs. Having reviewed the evidence that white dwarfs of mass M <0.5M⊙ are expected to be formed only in binary systems, I present in chapter 2, spectroscopic observations and analysis leading to mass determinations for 227 white dwarfs, 183 of which had no prior spectroscopically determined mass. The mass determination program successfully identified a new sample of low mass white dwarfs which could be followed up with radial velocity measurements to detect new DD binary systems.
The use of these radical velocity measurements to determine new orbital periods and mass ratios are described in chapters 3 and 4 respectively. I have more than doubled the numbers of known orbital periods and mass ratios for detached DD binaries. These new results have shown that current theoretical orbital period distributions are broadly consistent with the observed data, which supports a value for the efficiency of common envelope ejection of αCE ≃ 1. However the mass ratio distributions do not appear to be consistent with observed values, which may require a reconsideration of the importance of different evolutionary channels in the formation of DD binaries.
University of Southampton
Moran, Christopher Kevin James
1999
Moran, Christopher Kevin James
Moran, Christopher Kevin James
(1999)
Using observations of detached double degenerate binaries to test theories of stellar evolution in close binary systems.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The work presented in this thesis is a study of how observational measurements of detached double degenerate (DD) binaries can be used to test our understanding of the evolution of close binary stars. Where close binary stars are defined as those which will interact via mass transfer as the stars evolve off the main-sequence.
The introduction describes the physical processes leading to the formation of both single and binary white dwarfs. Having reviewed the evidence that white dwarfs of mass M <0.5M⊙ are expected to be formed only in binary systems, I present in chapter 2, spectroscopic observations and analysis leading to mass determinations for 227 white dwarfs, 183 of which had no prior spectroscopically determined mass. The mass determination program successfully identified a new sample of low mass white dwarfs which could be followed up with radial velocity measurements to detect new DD binary systems.
The use of these radical velocity measurements to determine new orbital periods and mass ratios are described in chapters 3 and 4 respectively. I have more than doubled the numbers of known orbital periods and mass ratios for detached DD binaries. These new results have shown that current theoretical orbital period distributions are broadly consistent with the observed data, which supports a value for the efficiency of common envelope ejection of αCE ≃ 1. However the mass ratio distributions do not appear to be consistent with observed values, which may require a reconsideration of the importance of different evolutionary channels in the formation of DD binaries.
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Published date: 1999
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Local EPrints ID: 464041
URI: http://eprints.soton.ac.uk/id/eprint/464041
PURE UUID: 43426a33-e437-4a1f-9251-a7fb063c7927
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Date deposited: 04 Jul 2022 21:01
Last modified: 04 Jul 2022 21:01
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Author:
Christopher Kevin James Moran
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