Homework 07
Please answer at least 4 of the following 5 questions correctly for full
credit:
Question 1
For main sequence stars: How do we use the Hertzsprung-Russell Diagram to
get the distance of a star that does not show any parallax?
Question 2
What is the difference between a spectroscopic or an eclipsing binary star
system and a visual binary star system?
Question 3
In terms of redshift and blueshift: What do we expect to observe in a
spectroscopic binary star system? Do we expect to make this observation on
the blackbody radiation for the stars in the system or for lines in their
spectra?
Question 4
What kind of radiation was used to discover the spiral structure of our own
Milky Way galaxy? Describe the changes in the hydrogen atom that lead to its
emission, and tell us why that radiation can get to receivers here on Earth,
i.e. why it can penetrate the obscuring dust throughout the galaxy as well
as the atmosphere around the Earth itself.
Question 5 (the quantitative one...)
When we talk about the lifetime of a main sequence star, we mean the time it
stays on the main sequence part of the Hertzsprung-Russel diagram.
What is the exponent in the mass-lifetime relationship for main sequence stars?
(Look at my lectures, not the book!) Who lives longer, the more or the less
massive stars? When you write down the proportionality between lifetime
L and mass M with the correct exponent, make sure the sign of
your exponent reflects the correct order of who lives longer. In other words:
think about what a negative or a positive exponent mean. Remember that
an expression with a negative exponent is the same as one over that same
expression with a positive exponent.
Please submit your answer as plain test in the main message body of an e-mail to
kai-1060-hw@physics.utah.edu
before midnight (MST) on March 13, 2008. Plain text in the main
message body of your e-mail means
Last modified: Fri Mar 7 16:39:33 MST 2008