8/27/03lsu - aei astrophysics1 the nonlinear development of instabilities in rotating stars and...
TRANSCRIPT
8/27/03 LSU - AEI Astrophysics 1
The Nonlinear Development of Instabilities in Rotating Stars and Binary Star Systems
Joel E. Tohline & Juhan Frank
Kevin Pearson
Shangli Ou, Mario D’Souza, Ravi Kopparapu, Vayu Gokhale
(Hopefully: Xiaomeng Peng & Ilsoon Park)
Former students: Kim New; John Cazes, Howard Cohl, Patrick Motl, Eric Barnes
8/27/03 LSU - AEI Astrophysics 2
Recent Focus
• Isolated, rotating stars– Dynamical, barmode instability
– (Secular) barmode instability in young Neutron Stars
– (Secular) r-mode instability in young Neutron Stars
• Binary star systems (late stages of evolution)– Tidal instability (stiff equations of state)
– Mass-transferring instabilities
• Formation of binary stars
8/27/03 LSU - AEI Astrophysics 3
Recent Focus
• Isolated, rotating stars– Dynamical, barmode instability
– (Secular) barmode instability in young Neutron Stars
– (Secular) r-mode instability in young Neutron Stars
• Binary star systems (late stages of evolution)– Tidal instability (stiff equations of state)
– Mass-transferring instabilities
• Formation of binary stars
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Movies
http://baton.phys.lsu.edu/tohline/LSUAEI.movies.html
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Principal Governing Equations
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Numerical Simulations
• Initial Models: Self-Consistent-Field Technique
• Explicit Time-Integration
• Finite-Difference Scheme– Uniform, Cylindrical Lattice
[typically, 1283 - 2563]
– Rotating Frame
– van Leer Advection
• Heterogeneous Computing Environment SuperMike: LSU’s 1024-processor, 2.2
TeraFlop Supercomputer
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Regions of Instability & Possible Evolutions
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Regions of Instability & Possible Evolutions
Movie #1 & Movie #2[Dynamical Barmode]
http://http://
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Regions of Instability & Possible Evolutions
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Hanford Observatory
LivingstonObservatory
Laser Interferometer Gravitational-wave Observatory (LIGO)
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Principal Governing Equations
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GR for (Dedekind) f-mode
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GR for (Dedekind) f-model = m = 2
5th derivative!
c5
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FGR for (Rossby) r-mode
[Lindblom, Tohline & Vallisneri (2001, 2002)]
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FGR for (Rossby) r-mode
[Lindblom, Tohline & Vallisneri (2001, 2002)]
(l = m = 2)
c7 !
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r-mode amplitude vs. time
[Lindblom, Tohline & Vallisneri (2001, 2002)]
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r-mode amplitude vs. time
[Lindblom, Tohline & Vallisneri (2001, 2002)]
Movie #3
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r-mode velocity field
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r-mode amplitude vs. time
[Lindblom, Tohline & Vallisneri (2001, 2002)]
Movie #4
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Neutron Star’s Angular Momentum, Erot, & Mass
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Sample Binaries
Exa
mpl
e B
inar
y S
yste
ms
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Roche Potential for Unequal-Mass Binary
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Sample Binaries
Exa
mpl
e B
inar
y S
yste
ms
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Movie #5 (top)
Movie #6 (side)
Movie #7 (vectors)