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Diameter in AU of a black hole with given mass?

  1. Sep 18, 2015 #1
    1. The problem statement, all variables and given/known data
    The Galaxy has a black hole with about 3 x 10^6 M☉. What is its diameter in AU?

    2. Relevant equations
    Not sure.

    3. The attempt at a solution
    3,000,000 solar mass, but not sure how to figure out the diameter in AU. Let's see...diameter of the sun is 1,000,000km

    3,000,000 x 1,000,000 = 3 x 10^12 km......one AU is 150 million km....1.5 x 10^8
    3x10^12km/1.5x10^8 = 2x10^4 AU???????
     
  2. jcsd
  3. Sep 18, 2015 #2

    berkeman

    User Avatar

    Staff: Mentor

    Welcome to the PF.

    What does your textbook say the relation is between the mass of the BH and its diameter?

    Alternately, you can look through the wikipedia article to find that relation... https://en.wikipedia.org/wiki/Black_hole

    :smile:
     
  4. Sep 18, 2015 #3
    I don't see it...
     
  5. Sep 18, 2015 #4
    Is this question about finding the Schwarzchild radius?
     
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