Problem Set 4
ASTR 5420 Stellar Evolution & Interiors
Due Wednesday, March 7, 2012
1. [10 points] The equation of radiative in a plane-parallel medium (such as a stellar
atmosphere) may be written as
dI (, )
= I (, ) S (, )
d
(1)
where is the cosine of th

Problem Set 5 Solutions
ASTR 5420 Stellar Evolution & Interiors
1. [10 points] Show for the ideal gas (/kT 1) that P = nkT is a general result
independent of whether the particles are relativistic, nonrelativistic, or anything in
between.
Solution: Begin

THERMONUCLEAR ENERGY
GENERATION
February 13, 2014
ASTR 5420
Average binding energy
February 13, 2014
ASTR 5420
Gamow peak
February 13, 2014
ASTR 5420
B = (mass of nucleons
mass of bound nucleus)c2
If A =number of nucleons,

Introduction to
Stellar Astrophysics
Prof. Hannah Jang-Condell
ASTR 5420 - Stellar Astrophysics
Tuesday, January 14, 14
Syllabus
Tuesday, January 14, 14
Basic Astronomical
Data for the Sun
by Eric Mamajek
https:/sites.google.com/site/
mamajeksstarnotes/

Problem Set 1
ASTR 5420 Stellar Evolution & Interiors
Due Friday, January 24, 2014
1. [10 points] In 2.3 of Kippenhahn, Weigert, and Weiss (KWW), we see that the central
pressure of a star can be estimated as
Pc =
2
2GM
.
4
R
As it turns out, the lower li

Problem Set 2
ASTR 5420 Stellar Evolution & Interiors
Due Friday, January 31, 2014
1. [10pts] In class, we discussed the constant density model for a star, which is completely
unrealistic, of course. A slightly less unrealistic model for a star of homogen

Problem Set 5
ASTR 5420 Stellar Evolution & Interiors
Due Friday, February 28, 2014
1. [6 points] Neutrinos are weakly interacting particles, so they easily escape from the
core of the sun. They can be a direct probe of the energy sources in the suns core

Problem Set 4
ASTR 5420 Stellar Evolution & Interiors
Due Friday, February 14, 2014
1. [10 points] Weak electron degeneracy. This problem deals with corrctions to
Maxwell-Boltzmann thermodynamics due to the eects of weak electron degeneracy
pressure. Supp

Problem Set 3
ASTR 5420 Stellar Evolution & Interiors
Due Friday, February 7, 2014
1. [10 points] Suppose a planet of mass mp is accreted onto a star of mass M and radius
R, with mp
M . Lets estimate R, the change in the radius of the star caused by
the a

Problem Set 1 Solutions
ASTR 5420 Stellar Evolution & Interiors
1. Show that
Pc =
2
3GM
= 1.34 1015 (M /M )2 (R /R )4 dyne cm2
4
8R
is a lower limit for the central pressure of a star, assuming hydrostatic equilibrium and
decreasing with respect to r.
(a)

Problem Set 1
ASTR 5420 Stellar Evolution & Interiors
January 21, 2014
1. Problem 1
(a) Problem 1a. Here are some equations:
3
Mr =
r
R
r
R
Mr =
If we set
M .
M ,
then show that decreases with r if < 3.
(b) If I want to typeset math in line, I do it like

Introduction to Radiative Transfer
ASTR 5420 Stellar Evolution & Interiors
Tuesday, January 28, 2014
1
1.1
Radiative Transport
Energy diusion
The general diusion equation, for particles diusing through space:
j = D n
where j is a ux in number of particles

Problem Set 2 Solutions
ASTR 5420 Stellar Evolution & Interiors
1. Linear density model. Assume a star whose density is a linear function of radius,
i.e.
r
( r ) = c 1
,
(1)
R
where c is the central density.
(a) Find an expression for the central density

Problem Set 1 Solutions
ASTR 5420 Stellar Evolution & Interiors
1. [10 points] Accretion energy
(a) [3 pts] Assuming a steady accretion rate of M , show that the accretion luminosity
is
GM M
(1)
Lacc =
R
Solution: The energy released by the infall of a ma

Problem Set 2 Solutions
ASTR 5420 Stellar Evolution & Interiors
1. [10 points] Show that
Pc =
2
3GM
= 1.34 1015 (M /M )2 (R /R )4 dyne cm2
4
8R
is a lower limit for the central pressure of a star, assuming hydrostatic equilibrium and
decreasing with respe

Problem Set 6
ASTR 5420 Stellar Evolution & Interiors
Due Friday, February 28, 2014
1. [4 points] Assume that at a certain frequency the opacity of the stellar plasma at the
surface of a given star is dominated by electron scattering. Estimate the depth (