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How can I know if two stars came from the same cluster?

  1. May 8, 2015 #1
    Hi everybody; I was wondering if there is a way of knowing if two stars came from the same open cluster knowing the distance fron these to the earth, the distance between them and their spectral types.

    If someone can pont me to a book or webpage where I can learm about that, it would be very helpfull.

    It's for an exercice in which I am asked about the possibility that the three stars from Orion's belt came from the same cluster since all sahre type B0.

    Thanks for reading.
  2. jcsd
  3. May 8, 2015 #2


    Staff: Mentor

  4. May 9, 2015 #3
    Indeed it does; so if I have three relatively close B0 stars I can assume that they might come from the same cluster since all of them are in the main phase?

    Another thing I can't find online is how to measure the absolute luminosity of a variable star; in this case I am tallking about Betelgeuse; the only information I have is that it's period if of six years an that it's relative visibility changes between 0.4 and 0.6. I have found online sone diagrams made by Henrietta Swan Levitt, but I can't find an equation which can give me the absolute magnitude.
  5. May 9, 2015 #4
    Apparently you are not the only one having difficulty determining the absolute magnitude of Betelgeuse. The following paper explains in why Mv = -5.85 is the most plausible explanation for Betelgeuse's absolute magnitude.

    A New VLA-Hipparcos Distance to Betelgeuse and its Implications - The Astronomical Journal, Volume 135, Number 4 (2008) (free issue)
  6. May 11, 2015 #5
    Nice, this helps me. Thanks.
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