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Earth and Space Sciences · 术语表

什么是 Jeans mass, Jeans length？

又称： Jeans mass · Jeans length

Definition 1.5 University Earth and Space Sciences — Year 2 · 第 1 章 — The Interstellar Medium and Star Formation

The Jeans mass $M_J$ and the Jeans length $R_J$ of a gas of given temperature and density are the mass and the radius above which a uniform sphere of that gas collapses under its own gravity (Proposition 1.4).

$(a) The Jeans mass against the density of particles for three temperatures (= 2.33). The shaded box marks the masses and densities of observed dense cores: at 10\, K their mass is close to the Jeans mass. (b) The free-fall time of : a third of a million years at 104 particles per cubic centimetre, ten times longer at 102.$

(a) The Jeans mass against the density of particles for three temperatures (

\mu = 2.33

). The shaded box marks the masses and densities of observed dense cores: at

10\,\mathrm{K}

their mass is close to the Jeans mass. (b) The free-fall time of Proposition 1.6: a third of a million years at

10^4

particles per cubic centimetre, ten times longer at

10^2

.

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