对金斯定则的几点认识

Understanding of Jeans Rule

用物理学基本定律可导出金斯经验定则,它似应称为金斯定则.该定则的速度、高度或能量等表述完全等效,可随意选用.用能量观点更容易解释此定则.满足金斯定则只是给定的粒子成为具有稠密大气的行星或卫星的主要大气成分的必要条件.该定则的适用范围可用方程或其图像表示,也能用诺模图确定;它适用于太阳系内的行星、卫星、小行星、流星体和像柯伊伯带天体与半人马族星这样的外太阳系天体.此定则现在仍有普遍的现实意义.

Jeans empirical rule has always been used in planetary physics. From the static equation of atmosphere, the equation of state for ideal gases, the law of gravitation and the law of Maxwell distribution, Jeans empirical rule can be derived. Therefore, it seems that Jeans empirical rule should be called Jeans rule. It can be formulated in three forms: in terms of velocity, height, or energy. These three formulations are completely equivalent. According to concrete situation, any one of these forms can be taken freely and used as a criterion, which define whether the atmospheric composition of a given species of particles at the planet surface will exist 'forever' or not. The factor in the energy formulation will be neither too large nor too small. According to statistical theory, taking the viewpoint of energy, Jeans rule can be explained more easily. The condition satisfying Jeans rule is only the necessary condition for a given species of particles to be major atmospheric composition of the planets which have dense atmosphere. Jeans rule is not only applicable for the planets and satellites in the solar system, but also suitable for the asteroids, meteoroids and outer solar system objects, such as Centaurs and Kuiper belt objects. The application scope of Jeans rule can be expressed with nomogram as well as denned by equations or by figures. Having been widely used for a long time, it still has a general practical significance in detecting age of planets in the solar system nowadays, especially for the research of outer solar system objects.