Thursday, March 11, 2010

More Astrophysics Notes

What determines the brightness of a star?

  • b = L / (4πd2) [W/m2]

What determines the luminosity of a star?

  • Assuming a blackbody radiator:

o L = σAT4

o σ = 5.67 x 10-8 [W/m2K4]

What determines the surface temperature of a star?

  • Wein's Law: T = (2.90 x 10-3(K·m))/ (λmax)

More massive stars are also more luminous.

Absolute magnitude (M) is the magnitude of a star when observed from 10 parsecs.

Relative magnitude (m) is the magnitude of a star when observed from the Earth (or nearby).

Stars radiate energy through hydrogen fusion.

Fg = GMm/d2

White dwarf- in equilibrium (not a black hole) due to "electron degeneracy"

1 parsec = 3.26 light-years

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