1993 Fiscal Year Final Research Report Summary
Studies on the Superfluid Vortices in Neutron Star Interious
| Project/Area Number |
04640275
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Astronomy
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| Research Institution | Rikkyo University |
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Principal Investigator |
SHIBAZAKI Noriaki Rikkyo University, Department of Physics, Associate Professor, 理学部, 助教授 (50206124)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBATA Shinpei Yamagata University, Department of Physics, Assistant Professor, 理学部, 助手 (90187401)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Neutron Star / Superfluid Vortex / Creep Motion / Pulsars / Gamma-Ray Bursts |
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| Research Abstract |
The vortex creep motion in the inner crust is one of mechanisms which couple the superfluid to the crust. We have already shown by the linear analysis that this coupling is unstable below a critical temperature. We have investigated how this instability develops after the onset, conducting the numerical calculations with nonlinear terms. The main results are summarized as follows.
1. The instability develops into a limit-cycle, in which the temperature and angular velocity difference between crust and superfluid oscillate.
2. This instabity is identified to be a frictional instability. The instability grows because the increase of friction due to the temperature increase dominates over the decrease of friction due to the decrease of angular velocity difference.
3. The internal torque becomes larger than the external torque in some phase of the oscillation and the crust is even spun-up.
We have also studied the energy release and particle acceleration in the neutron star magnetosphere. The main results are as follows.
1. The global structure of the magnetosphere has been determined for the first time, solving the Grad-shafranov equation. We found that the energy disspation in the magnetosphere is required in order to determaine the structure.
2. The sudden discharge caused by a perturbation in the magnetosphere of a dead pulsar cannot yield an energy release rate larger than that of the magnetic dipole radiation. This makes the discharge model for the gamma-ray bursts unlikely.
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