Lecture 4 - Orbital Mechanics (1/21/99)
Blackbody --- | ---
Chapter 1, 12-1 (ZG4)
pages 12 - 16
HST Coronograph image of binary star Wolf 424, with separation
The companion may be a brown dwarf. (Courtesy
||What can we learn from binary stars?
||Newton's Laws of Gravitation
||What determines the relative orbit
of a 2-body system?
- Weighing the Stars
- When did William Herschel discover that the Castor system was
a binary star?
- What percentage of stars in the solar neighborhood are members of
multiple star systems?
- Why are apparent doubles not considered real binary stars?
- How are binary stars used to determine stellar masses?
- How are the luminosity and temperature of stars measured?
- What are the four primary physical parameters of stars?
- What is a visual binary?
- What is a spectrum binary?
- Why are spectroscopic binaries useful?
- What can we learn from eclipsing binary systems?
- Orbital Mechanics Revisited
- Kepler's 1st Law states that orbits are ellipses with the
Sun at one focus. How does this apply to binary stars?
- What is the eccentricity of an ellipse?
- What is the center of mass?
- What is the reduced mass and what is its role in the
center of mass coordinates?
- What is the energy equation for a binary system?
- What is the angular momentum equation?
Review of Mechanics:
For a review of orbital mechanics, especially Kepler's Laws and Newton's
Laws, see Chapter 1 in ZGS (especially 1-2 through 1-4). Also, look
at the Astro 11 lectures
Note that we will be using mechanics all through the semester so it
is worth spending time now to really get into it. In particular, we will
be studying the motions of stars in our galaxy, galaxies in clusters of
galaxies, and the dynamics of the Universe as a whole which will build
on these fundamental ideas!
For those of you who did not take Astro 11, you can review these subjects
in the above-mentioned chapters of the textbook, or look at my lecture notes
placed on reserve in the Math-Physics library on the 3rd floor of DRL.
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Steven T. Myers