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The Jeans mass is named after the British physicist Sir James Jeans, who considered the process of gravitational collapse within a gaseous cloud. He was able to show that, under appropriate conditions, a cloud, or part of one, would become unstable and begin to collapse when it lacked sufficient gaseous pressure support to balance the force of gravity.
Sir James Hopwood Jeans OM FRS [1] (11 September 1877 – 16 September 1946 [2]) was an English physicist, mathematician and an astronomer.He served as a secretary of the Royal Society from 1919 to 1929, and was the president of the Royal Astronomical Society from 1925 to 1927, and won its Gold Medal.
Firehose instability (a.k.a. hose instability), not to be confused with the similarly named Firehose instability in galactic dynamics; Fish instability, Free electron maser instability, Gyrotron instability, Helical (Helix) instability, Jeans instability, [23] [24] Magnetic buoyancy instability. Interchange instability (a.k.a. flute instability ...
Jeans Equation simulations place limits on the size of this halo. An example of such an analysis is given by the constraints that can be placed on the dark matter halo within the Milky Way. Using Sloan Digital Sky Survey measurements of our Galaxy, researchers were able to simulate the dark matter halo distribution using Jeans equations. [8]
The square root of the ratio is about 6. I dislike the formula here as it makes Jeans Mass for Bernard 68, 10.117 solar masses and Cambridge's formula makes Jeans Mass 1.662 solar masses assuming it is all molecular hydrogen not just mostly. Anyway, it is advertised in Wikipedia as a collapsing cloud a star that will be born in 200,000 years.
The book was denounced by the Cambridge philosopher Ludwig Wittgenstein, "Jeans has written a book called The Mysterious Universe and I loathe it and call it misleading. Take the title...I might say that the title The Mysterious Universe includes a kind of idol worship, the idol being Science and the Scientist."
After the instability has run its course, the system is typically "hotter" (the motions are more random) or rounder than before. Instabilities in stellar systems include: Bar instability of rapidly rotating disks; Jeans instability; Firehose instability [4] Gravothermal instability [5] Radial-orbit instability
Initially, the long-to-short axis ratio of the galaxy is 10:1. After the instability has run its course, the axis ratio is approximately 3:1. Note the boxy shape of the final galaxy, similar to the shapes of bars observed in many spiral galaxies. The firehose instability (or hose-pipe instability) is a dynamical instability of thin or elongated ...