exc3 - Introduction to Astrophysics 0321.3108 Exercise 3 1...

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Unformatted text preview: Introduction to Astrophysics 0321.3108 Exercise 3 1. In class we showed that in thermal equilibrium N ( H + ) N ( H ) = 1 N ( e ) 2 πm e k B T h 2 3 / 2 exp- 1 . 6 × 10 5 T , (1) where N ( H + ) is the proton number density, N ( H ) is the atomic hydrogen number density, N ( E ) is the electron number density and T is the gas temperature. For a typical density in a stellar photosphere: ∼ 5 × 10 14 cm- 3 , find the temperature such that N ( H + ) /N ( H ) = 1. Guidance: assume that the density of the electrons is the same as the density of the protons. The last equation must be solved numerically! 2. Find the frequencies of the spectral lines: Ly α , Ly β , Ly γ , H α , H β and H γ . Explain your derivations. 3. Suppose a star of total mass M and radius R has a density profile ρ = ρ c (1- r/R ), where ρ c is the central density. a. Find M(r). b. Express the total mass M in terms of R and ρ c ....
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This note was uploaded on 02/27/2012 for the course PHY 321 taught by Professor Sternberg during the Spring '10 term at Tel Aviv Uni..

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exc3 - Introduction to Astrophysics 0321.3108 Exercise 3 1...

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