2003 Fiscal Year Final Research Report Summary
Hydrodynamic Pulsation Modes of Multi-frequency Radiative Transfer for Mass-losing Early Type Stars
| Project/Area Number |
14540229
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Astronomy
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| Research Institution | Tohoku Gakuin University |
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Principal Investigator |
AIKAWA Toshiki Tohoku Gakuin University, Fac.Liberal Art, Prof., 教養学部, 教授 (10221029)
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| Project Period (FY) |
2002 – 2003
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| Keywords | stars / stellar pulsation / radiative transfer / post-AGB stars / chaos |
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| Research Abstract |
Hydrodynamic Pulsation models with an improved radiative transfer is studied. In this study, we concentrated in unified treatment of radiative transfer for linear analysis and non-linear simulation modeling.. As the first step of this study, we took non-diffusion approximation as the approximation of radiative transfer instead of equilibrium diffusion approximation. We have the fallowing results.
1. We constructed computer codes for both linear analysis and non-linear simulation. We may extend the codes for the variable Eddington factor approximation for more improved treatment of radiative transfer. We applied the present codes to post-AGB stars as am example of less-massive supergiants stars as well as classical Cephieds.
2. For linear analysis we compare the pulsation periods and the growth rate of models. The non- equilibrium approximation yields very small change for both the quantities. For non-linear simulation, we compared the time variations of observable quantities at the photosphere of models. The new approximation yields very small changes on these values.
3. We have an interesting result on irregular pulsation of the post-AGB stars. It is known that pulsation model for post-AGB stars shows irregular pulsation fix luminous supergiant stars. The new model yields quite large different time evolution of irregular pulsation compared with ones which is obtained with the model of traditional diffusion approximation for the same values of model parameters. We suspect that the difference comes form the characteristics of chaos. In chaos system, a small change of basic equations may yield great differences of time evolution at later time, even if the calculation starts with the same initial conditions for the same model That is the case of the behavior.
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Research Products
(3 results)
