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Unformatted text preview: Astro 405/505, fall semester 2005 Additional problems solutions Problem 1: plasma The plasma frequency is p 10 8 Hz and the Debye length D . 02 cm. For the plasma parameter we obtain g 1 / 3200 so we are dealing with a plasma and must employ kinetic theory to properly understand its inner workings. The Coulomb collision frequency is ee 10 4 Hz. The neutral-neutral collision frequency is a few hundred Hertz and the mean free path is about l n 10 3 cm. This is much smaller than the system size of R 10 15 cm, so I can use hydrodynamics to describe the large-scale ( 10 3 cm) physics of the collapse. Problem 2: emission spectra The source function is a constant and therefore the solution to the radiation transport equation would be S = A B 2 I = A B 2 (1- exp(- )) = B - 3 L where LK is the length of the line-of-sight through the source....
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- Fall '08