Understanding Jeans Instability & Masses

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The discussion focuses on understanding the Jeans instability, Jeans mass, and Jeans length, particularly the variables involved in the formulas. The user expresses confusion about the symbols used, specifically m_H (hydrogen) and m_p (proton), and seeks clarification on the units and their implications. There is a mention of the average molecular mass (μ) in the context of the Jeans mass formula. Additionally, the user questions whether the Jeans instability applies to all masses of interstellar medium (ISM), noting that larger astronomical objects often require additional factors for accurate modeling. The conversation emphasizes the need for clarity on these concepts to better grasp their application in astrophysics.
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I'm trying to understand all the properties of the Jeans instability, the Jeans mass and the Jeans length. I understand the mathematics behind it, though not all the variables. There is a m_{H}[\itex] or I've also seen it as m_{p}[\itex] in the Jeans length and Jeans mass. The formula is as follows:<br /> <br /> M_{J}=(\frac{5×k_{B}×T}{G×μ×m_{H}})^{1.5}×(\frac{3}{4×\Pi×\rho_{0}})^{.5}[\itex], I know that μ is the average molecular mass. <br /> <br /> Can someone help me understand this please? I'm a bit confused. I tried looking at the units, though couldn't figure it out.<br /> <br /> Also, another question about it: Does it work for all masses of ISM? From what I picked up in class, most things don't work for very large objects in astro, and they need more "fudge factors" to work. Is that the same for the Jeans instabilities?
 
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Dear Cmertin,

H stands for hydrogene, p for proton. The nass measured in that unit is \mu!

All the best,
Yuu
 
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