Download Homework 4

Astronomy 100
Name:
Homework 4
Due November 2, 2012 at 5 p.m., either electronically or on paper.
1. If a protostar is forming out of a cold molecular cloud, how can its luminosity be
upto one hundred times as large as the luminosity of the star it will become?
2. Why can’t stars have masses greater than 150 to 200 solar masses? In other words,
what physical limitations are there on the maximum size of stars?
3. Describe bipolar outflow in protostars. What happens to the protostar as a result of
this?
4. In figures 3.5 and 3.6 (pp. 74 and 75 in the text), the text shows what is called the
“main sequence turnoff” for various open clusters (the text does not call it that,
but astronomers use the term). How is the “main sequence turnoff” used to determine
the age of an open cluster?