Construction of a solar nebula model considering the effect of magnetic field

考虑磁场影响的太阳星云模型构建

基本信息

批准号：
06832011
负责人：
SEKIYA Minoru
金额：
$ 1.34万
依托单位：
KYUSHU 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：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06832011/
关键词：
solar system solar nebula magnetic field protoplanetary disk chondrule cosmic dust dust 原始式惑星系円盤ダイナモ

项目摘要

(1) Variation of the dissipation rate of the maganetic field due to the settling and the growth of the dust particles in the solar nebula is calculated. As a result, the dissipation rate of the magnetic field is found to decrease due to the settling and the growth of the dust. However, the magnetic field does not grow as to affect the evolution of the solar nebula. (2) The revision of the momentum transfer rate between an electron and a neutron is found to have little effect on the dissipation rate of the magnetic field. (3) Radiative equilibrium temperature of the solar nebula is calculated. As a result, temperature is found to be lower than of Hayashi's model (1981), and there are possibility that the nebula become unstable against convection even if it is transparent. (4) Numerical code of SPH method to calculate the evolution of the solar nebula due to eddy viscosity is developed. (5) Condition of chondrule formation is made clear, by observing compound chondrules and using the gravitational istability condition of the dust layr. Chondrules were probably made in the region much inner than the Asteroid belt. (6) Chemical reactions and condensation process on the dust particles in the protoplanetary disks are calculated. Especially, behavior of CO molecules are investigated in detail. As a result, it is found that almost all the CO molecules condense for less than 20 K, i. e. outer than 200 AU from the central star. (7) Numerical simulation of the entry of cosmic dust is performed. This simulation give the temperature experienced by a cosmic dust as a function of the entry angle and speed into the atmosphere.

(1)计算太阳星云中尘埃粒子沉降和生长引起的磁场耗散率的变化。结果，发现磁场的耗散率由于灰尘的沉降和生长而降低。然而，磁场的增强并没有影响太阳星云的演化。 (2)发现电子和中子之间动量传递率的修正对磁场耗散率影响很小。 (3)计算太阳星云的辐射平衡温度。结果发现，温度低于林模型（1981）的温度，并且即使星云是透明的，也有可能对对流变得不稳定。 (4) 开发了计算太阳星云涡粘演化的SPH方法的数值代码。 (5)通过观测复合球粒并利用尘埃层的重力不稳定条件，明确了球粒的形成条件。球粒可能是在比小行星带更内部的区域形成的。 (6)计算了原行星盘中尘埃粒子的化学反应和凝结过程。特别是，详细研究了 CO 分子的行为。结果发现，几乎所有的CO分子在低于20 K的温度下发生凝结，即。 e.距离中央恒星超过 200 个天文单位。 (7)对宇宙尘埃进入进行数值模拟。该模拟给出了宇宙尘埃所经历的温度与进入大气层的进入角度和速度的函数关系。