1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Initial Mass Function Question (white dwarfs, neutron stars and black holes)

  1. Apr 13, 2016 #1
    1. The problem statement, all variables and given/known data

    Calculate the number of white dwarf, neutron star and black holes the galaxy will have after 5Gyr of evolution.

    M<8(solar mass) for white dwarf

    8(solar mass) < M < 40(solar mass) for neutron star

    M > 40(solar mass) for black hole

    Initial mass function is ξ(M) = AM-s where s = 2.35 in the Milky Way, M is the mass in solar units and A is a normalisation constant.

    2. Relevant equations

    Total number of stars formed with masses between M1 and M2 is

    N = ∫M2M1 ξ(M) dm

    3. The attempt at a solution

    In our case, N = A(∫80.1M-2.35dm + ∫408M-2.35dm + ∫10040M-2.35dm)

    ∴ N = -(A/1.35) ((-22.33) + (-0.053) + (-4.88x103))

    So White Dwarf Total = 16.5 A
    Neutron Star Total = 0.039 A
    Black Hole Total = 3.61x10-3A

    How do I account for the 5Gyr of evolution within my answer as at the moment I believe all I have calculated is the number of stars formed between the masses specified?
     
  2. jcsd
  3. Apr 16, 2016 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    I'm not sure if the questions is asking about that, but (a) you might have to determine A or (b) you should take into account existing stars and stellar remnants, or even (c) take into account that some stars live longer than 5 Gyr.

    And keep in mind that the present distribution of stellar masses and the distribution of stellar masses of new stars are completely different things due to the different lifetime.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted