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Chandrasekhar’s
(1960) formula:
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dv/dt = -(v/v3)16π2(ln Λ)G2m(m+M)∫f(v)v2dv
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where
Λ is a factor of order 1 involving the masses,
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impact
parameter and initial velocity, f is the stellar
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density,
M is the intruder, m is the stellar mass.
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If
the intruder is mass, M >> m, then
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dv/dt ~ -v 16π2(ln Λ)G2mM
f(0)
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So
the force proportional to velocity in this case, a
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viscous
friction. Concerned with the mass
density of
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stars,
not individual masses. Force
dependent on M,
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intruder
mass. The FORCE goes as mass
squared.
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