Question
Find the approximate mass of the luminous matter in the
Milky Way galaxy, given it has approximately $10^{11}$ stars of
average mass 1.5 times that of our Sun.
Final Answer
$3\times 10^{41} \textrm{ ly}$
Solution Video
OpenStax College Physics Solution, Chapter 34, Problem 1 (Problems & Exercises) (0:31)

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Video Transcript
This is College Physics Answers with Shaun Dychko. We are going to estimate the mass of all the luminous matter in the milky way galaxy. We assume there are 10 to the 11 stars each having an average mass of one and a half times the mass of our Sun so it's one and a half solar masses per star and then times by the number of kilograms of mass in the Sun. This gives 3 times 10 to the 41 kilograms total mass of all the stars in the milky way.