AST 301
Homework #7
Due Friday March 21
1. (Problems 2 & 3 in chapter 10)
a) The Ring Nebula in Lyra (p. 190) is a planetary nebula with an angular diameter of 72 arcseconds and a
distance of 5000 ly. What is its linear diameter? (Hint: see By The Numbers 3-1, or convert 72 arcsec to
degrees and use the formula we've used before.)
b) If the Ring Nebula is expanding at 15 km/s, typical of a planetary nebula, how old is it?
2. In a few sentences say what a planetary nebula is and how it forms.
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