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Figuring out mass of a star based on diameter

  1. Oct 4, 2008 #1
    How do you find the mass of a star based on its diameter? are there other factors that play into it and other things like that or is it just an equation???
  2. jcsd
  3. Oct 4, 2008 #2


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    For main sequence stars you can use


    with R being the diameter. For non-main sequence stars, this doesn't hold however. For instance, when our Sun expands into a red giant, its mass will not increase but its radius will do so greatly. Another Example is Betelgeuse, a super giant with a mass 14 times that of the Sun and a radius 630 times as much.
  4. Oct 5, 2008 #3
    i can figure out that non main sequence stars hold the same mass because its just less matter per square mile or sqaure yoctometer or whatever measure u want to use.
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