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Unformatted text preview: Homework # 10, due 9 May (no penalty up to 17 May) 1. Compute the deﬂection angle of a star whose light just grazes the
limb of the Sun. Also compute the deﬂection angle of a star whose
light just grazes the limb of a 1.4M neutron star, if the neutron
star was at the same distance from the Earth as the Sun. State
2. Use the Plummer potential model, with a value of a = 100 kpc,
together with the Viral theorem to infer a value for galaxy masses
in Fig. 7.3 assuming that all the galaxies have the same mass. Do
not include Stephan’s Quintet in this estimation.
3. From dynamical friction, determine that the LMC will sink into
the Milky Way’s center in about 3 Gyr. About how long will
it take a typical Galactic globular cluster to sink into the Milky
Way’s center? State your assumptions.
4. There is a ﬁgure in the text showing that the luminosity in X-rays
LX increases as the cube of the X-ray temperature TX . Can you
provide an analytic argument showing why this is? ...
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- Spring '11