Galaxies Lecture 15

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Leaky Box Model

  • Leaky Box Model
    • Gas leaves system via galactic winds from SNe

Where is the mass in stars, and is the mass in stars and gas.

    • Going through the same reasoning as before, we find:
    • This can explain the G dwarf problem if 90% of gas is blown out of the galaxy. This doesn’t match observations for the Milky Way, but it does work for dwarf irregulars.
  • Accreting Box Model
    • For large spirals, gas only accounts for a small amount of the total mass. Some infalling gas immediately turns into stars.

but .

    • Working through this model, we find that:

Note the log (as opposed to exponential) dependence.

    • Choosing , and using , we find:

This solves the G dwarf problem.