The Saha Equation: Understanding Ionization
ASTR211
20 October 2015
Group number:
Group members names:
Goals
1. Understand the process of thermal ionization described by the Saha equation
2. Understand how ionization is relevant to atoms in the atmosphere

Things are Heating Up:
Understanding Temperature
ASTR211
15 October 2015
Group number:
Group members names:
Goals
1. Understand the relation between temperature and population of energy states as given
by the Boltzmann equation
2. Understand the Maxwell-B

The Doppler Shift and Its Uses
ASTR211
22 October 2015
Group number:
Group members names:
Goals
1. Understand the physical origin of the Doppler eect for light
2. Understand how the Doppler eect can be used for interesting astrophysical measurements
You w

Lines in Stellar Atmospheres
ASTR211
29 October 2015
Group number:
Group members names:
Goals
Goals for this exercise:
1. Understand how to calculate an absorption line in a stellar atmosphere
2. Understand the meaning of equivalent width in describing ab

The Formation of Absorption Lines in a Stellar
Atmosphere
ASTR211
27 October 2015
Group number:
Group members names:
Goals
Goals for this exercise:
1. Understand the ingredients in the formation of an absorption line
You will need to download the newest v

The Electromagnetic Spectrum
Photons are one of the three primary ways of transporting energy from one place to another,
the other two being conduction (thermal contact), and convection (bulk motion of matter).
We will come back to this when we talk about

Demonstrations in Light and Spectroscopy
ASTR211
1 October 2015
Group number:
Group members names:
Goals
1. To understand emission of spectral lines
2. To understand some features of thermal continuum emission
3. To understand absorption lines
1
We are go

Blackbody Radiation and Continuum Spectra
ASTR211
3 November 2011
Group number:
Group members names:
Goals
Goals for this exercise:
1. Understand the Planck function for blackbody radiation, as a function of both wavelength and frequency
2. Use knowledge

Interaction of Light and Matter
ASTR211
6 October 2015
Group number:
Group members names:
Goals
1. Understand the units for electrostatic forces and the the relation of the hydrogen atom
to the gravitational two-body problem
2. Use and understand the form

Atoms and Atomic Processes
ASTR211
13 October 2015
Group number:
Group members names:
Goals
1. Understand some basic principles of the interaction of light and charged particles with
matter
2. Gain practice with calculating energies and emitted wavelength

ASTR211: Introduction to Astrophysics I
Problem Set #6
Due at the beginning of class 5 November 2015
1. A simple stellar model. Suppose a star can be treated as a sphere of radius R =
5.2 109 m with a surface temperature of 28,000 K, which radiates as a b

ASTR211: Introduction to Astrophysics I
Problem Set #7
Due at the beginning of class 24 November 2015
1. Consider the following HR diagram with 11 objects, which we will refer to as stars,
even though not all are stars by the denition of actively fusing h

ASTR211: Introduction to Astrophysics I
Problem Set #5
Due at the beginning of class 29 October 2015
1. The size of highly excited hydrogen. (You may recognize this as Questions 6 and 7 from
In-Class Exercise 11, which we didnt get to in class.)
(a) Compu

Orbital Dynamics
ASTR211
17 September 2015
Goals for this exercise:
1. To understand the equations regarding properties of orbits in the two-body problem
2. To practice symbolic manipulation of those equations
3. To use symbolic reasoning to answer questi

Features of Orbits in the Two-Body Problem
ASTR211
17 September 2015
The Eective Potential
Lets go back to the expression for the energy of the two body problem, written in terms
only of the scalar function r(t) (and its derivative) which gives the separa

Keplers Laws of Planetary Motion
ASTR211
1 September 2015
Keplers Laws may be stated:
1. Planets move in elliptical orbits with the Sun at one focus of the ellipse. Nothing is at
the other focus.
2. The motion of the planet sweeps out equal areas in equal

Energetics in the Two Body Problem
ASTR211
10 September 2015
Energy and Newtons Laws
Recall that Newtons 2nd Law denes force
F = ma = mv =
d(mv)
=p
dt
The work or energy is dened as
F dr
E=
(1)
path
A form of energy youre probably familiar with is kinetic

Gravity, Ordinary Dierential Equations, and
Non-dimensionalizing
ASTR211
3 September 2015
Solving the Equation of Newtons Second Law
Lets start with a simple problem youve denitely solved before, even if not in quite the
way well do it here. We consider a

Setting Up the Two Body Problem
ASTR211
8 September 2015
The Two-Body Problem
The full problem we want to solve is that of two bodies of mass m1 and m2 interacting only
under their mutual gravitational attraction. This is a very important problem in astro

The Big Picture (Thus Far)
ASTR211
22 September 2015
At this point in the course it is well worth taking a little time to think about the bigger
picture of what we are learning, and how it relates to science more broadly. Here are some
thoughts:
1. Newton

ASTR211: Introduction to Astrophysics I
Problem Set #4
Due at the beginning of class 15 October 2015
1. Consider a single photon of wavelength 500 nm (green light).
(a) How fast would an electron have to be going to have the same momentum as this
photon?