• Q
4 The Ring Nebula is a photogenic planetary nebula in the constellation Lyrae. The Ring has an angular diameter
of 72 arcseconds, and we
estimate it is 5000 light years away. What is its linear diameter? (Hint: you will need to dig up the
good old small angle
formula from chapter 3.)
•a.0.17 light years
•b.0.34 light years
•c.1.7 light years
•d.3.4 light years
•e.17 light years
•
•Angular diameter /206265 arcsec = linear
diameter/distance
•Straightforward
without unit conversions needs.
Linear diameter = (72/206265)x 5000 light years = 1.7 light years.
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