Persistent Link:
http://hdl.handle.net/10150/280579
Title:
Hydrodynamics, nucleosynthesis, and mass loss in massive stars
Author:
Young, Patrick Allen
Issue Date:
2004
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
I test the predictive power of the stellar evolution code TYCHO. Systematic errors are present in the predictions for double-lined eclipsing binary stars when only standard physics common to the majority of stellar evolution codes is included. A mechanism for driving slow circulation and mixing in the radiative regions of stars is identified in numerical simulations of convection and a physical theory developed. Mixing is caused by dissipation of inertial waves driven by the interaction of convective fluid motions with the boundary of the convection zone. Evolutionary calculations incorporating this physics are tested in several observational regimes. Light element depletion in young clusters, turnoff ages of young clusters with brown dwarf Li depletion ages, and evolution of carbon stars on the asymptotic giant branch are all predicted satisfactorily. Tests of solar models yield good agreement with surface observables, chemical abundances, helioseismological data, and neutrino fluxes. The predictive accuracy of a non-calibrated, state-of-the-art stellar evolution code is ∼7% for surface observables. The main sequence sun is relatively easy to model, so this gives an estimate of our minimum predictive error. The solar models also highlight problems with uniqueness of evolutionary tracks converging on a given point and the potential for avoiding the effects of missing physics by calibration. A reanalysis of the binary sample with the more complete physics shows a dramatic improvement in the accuracy of the models. The potential for avoiding the effects of missing physics by calibration is explored. A TYCHO model for a late AGB star is used for the boundary conditions on a hydrodynamic simulation of proto-planetary nebula evolution as an illustration of the unified technique. NaCl and NaCn are observed at large radii in the Egg Nebula. These molecules require high densities to form, which are difficult to explain at large distances from the star. The 2-D simulation of a fast wind interacting with earlier mass loss produces clumps of material through a thermal instability with the necessary conditions for formation of the molecules. In conclusion, the effects of the more complete physics on the core size and abundance profiles of a massive star during core Si burning are examined as an example of future developments.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Physics, Astronomy and Astrophysics.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Astronomy
Degree Grantor:
University of Arizona
Advisor:
Arnett, David

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleHydrodynamics, nucleosynthesis, and mass loss in massive starsen_US
dc.creatorYoung, Patrick Allenen_US
dc.contributor.authorYoung, Patrick Allenen_US
dc.date.issued2004en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractI test the predictive power of the stellar evolution code TYCHO. Systematic errors are present in the predictions for double-lined eclipsing binary stars when only standard physics common to the majority of stellar evolution codes is included. A mechanism for driving slow circulation and mixing in the radiative regions of stars is identified in numerical simulations of convection and a physical theory developed. Mixing is caused by dissipation of inertial waves driven by the interaction of convective fluid motions with the boundary of the convection zone. Evolutionary calculations incorporating this physics are tested in several observational regimes. Light element depletion in young clusters, turnoff ages of young clusters with brown dwarf Li depletion ages, and evolution of carbon stars on the asymptotic giant branch are all predicted satisfactorily. Tests of solar models yield good agreement with surface observables, chemical abundances, helioseismological data, and neutrino fluxes. The predictive accuracy of a non-calibrated, state-of-the-art stellar evolution code is ∼7% for surface observables. The main sequence sun is relatively easy to model, so this gives an estimate of our minimum predictive error. The solar models also highlight problems with uniqueness of evolutionary tracks converging on a given point and the potential for avoiding the effects of missing physics by calibration. A reanalysis of the binary sample with the more complete physics shows a dramatic improvement in the accuracy of the models. The potential for avoiding the effects of missing physics by calibration is explored. A TYCHO model for a late AGB star is used for the boundary conditions on a hydrodynamic simulation of proto-planetary nebula evolution as an illustration of the unified technique. NaCl and NaCn are observed at large radii in the Egg Nebula. These molecules require high densities to form, which are difficult to explain at large distances from the star. The 2-D simulation of a fast wind interacting with earlier mass loss produces clumps of material through a thermal instability with the necessary conditions for formation of the molecules. In conclusion, the effects of the more complete physics on the core size and abundance profiles of a massive star during core Si burning are examined as an example of future developments.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectPhysics, Astronomy and Astrophysics.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineAstronomyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorArnett, Daviden_US
dc.identifier.proquest3132275en_US
dc.identifier.bibrecord.b46708029en_US
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