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Snowplow model of a supernova remnant

  1. Mar 23, 2008 #1
    Suppose a spherical shell identified as a supernova remnant is observed with radius r and
    with outward expansion speed v. Assume the mass density of the ambient medium to have
    the uniform value "ro_0". then the supernova remnant must have swept up mass M = ((ro_0)*4pi*r^3)/3.
    Let the original mass M_0 be ejected at speed v_0. If we ignore communication between
    different parts of the shell (via the thermal pressure of the hot interior), and suppose that
    each piece of the shell preserves its outward linear momentum as it sweeps up more material initially at rest, we have the snowplow model.

    a) Show that the snowplow model implies
    (M +M_0)v = M_0*v_0.

    b) The original kinetic energy E_0 of the ejected material equals (M_o*(v_0)^2)/2
    0/2. The present
    kinetic energy E of the shell equals ((M + M_0)v^2)/2. Show that the ratios E/E_0 and v/v_0 are given by:
    E/E_0 = v/v_0 = M_0/(M +M_0).
  2. jcsd
  3. Mar 23, 2008 #2


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    Tuugii! When did you show up, buddy?
  4. Mar 24, 2008 #3
    hey Skip! :)

    I am a newbie here. Looking for some discussions on some problems related to my astro class.
  5. Mar 25, 2008 #4


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    Gold Member

    Welcome, Tuugii!! If you will post this problem in the Homework section and follow the format for posting, you will likely get some help pretty soon. You're expected to state the problem clearly, with any variables, and take a shot at dissecting/solving the problem so that the homework helpers can figure out where your problem-solving is breaking down.

    If you could come to Maine, you wouldn't be missing Mongolia this winter!
  6. Mar 26, 2008 #5
    wow that picture looks awesome!

    I'll visit your place at some point of this 4 years! :)


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