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A STUDY ON MECHANISM AND STRUCTURE OF RELATIVISTIC STELLAR WIND FROM ROTATING MAGNETOSPHERES

旋转磁层相对论性星风的机制和结构研究

基本信息

批准号：
05640301
负责人：
SHIBATA Shinpei
金额：
$ 0.96万
依托单位：
DEPARTMENT OF PHYSICS,YAMAGATA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

The main aim of this project is to clarify the effeciency of acceleration of the relativistic plasma outflow which is ejected from the rotating strongly magnetized objects in space. The efficiency is defined by how much fraction of the electromagnetic energy flux, which is dominant at the root of the stellar wind, is converted into plasma kinetic energy.At the fisrt year of this project, we approximately solved the magnetic field structure, which is believed to govern the efficiency. This is done by solving the so-called 'Grad-Shafranov' equation. We have obtained the field structure which is like the diple near the star and gradually modifed to the radial-alike open structure.At the second year, the field-aligned equation is solved under the obtained field structure in orger to get the efficiency. The field-aligned solution is chosed so that it start from the plasma source, passes throught the Alfven-critical point, and then passes throught the fast-critical point. It has been known that if the field structure is perfectly radial and the plasma is cold, then the fast-critical point is at infinity, and the efficiency is quite small. Contrarily, under the field structure we obtained in this project, we find that the fast-critical point moved inward to near the light cylinder, and very hight efficiency is obtained.Observationary, the relativistic wind from the Crab pulsar shows a high efficiency so our theory may account for this observational result.

本项目的主要目的是研究空间强磁化旋转物体喷射出的相对论等离子体外流的加速效率。效率的定义是恒星风根部占主导地位的电磁能通量转化为等离子体动能的比例，在本项目的第一年，我们近似求解了磁场结构，这被认为是决定效率的因素。这是通过求解所谓的“Grad-Shafranov”方程来完成的。我们得到了类似于星星附近的偶极子结构的场结构，并逐渐改变为类径向的开放结构，第二年在得到的场结构下求解场向方程，得到效率。场向解的选择是从等离子体源开始，向右通过阿尔芬临界点，然后向右通过快临界点。我们已经知道，如果场结构是完全径向的，等离子体是冷的，那么快临界点是在无穷远，效率是相当小的。首先，在我们所得到的场结构下，我们发现快临界点向内移动到了光柱附近，从而获得了很高的效率，而在观测上，来自蟹状星云脉冲星的相对论风也表现出了很高的效率，因此我们的理论可以解释这种观测结果。