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% (C) 2010 by Eugeniy Mikhailov, <evgmik@gmail.com>
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\begin{document}
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\newcommand{\hw}[1]{%
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		\Large  \bf Homework #1%
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\hw{13}

\problem{Problem 1 (5 points)}
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In class, I misquoted the oscillation period of the Sun with respect to the
galaxy disk. Calculate the correct value assuming that density
0.15~M$_\odot$/(pc)$^3$.

\problem{Problem 2 (5 points)}
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Using derivations of above problem, find the maximum deviation/height of
the Sun above the galaxy disk median. Does the Sun belong to the thin or
the thick disk?  The current velocity of the Sun in direction away from the
disk is $\omega_\odot = 7.2$~km/s and height above disk is $z_\odot = 30$~pc.

\problem{Problem 3 (5 points)}
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A neutron star with $R=10$~km and mass $M=2 M_\odot$ has observed
luminosity of $L_\odot$, assuming that we are far away from this star, what is
its luminosity at the surface of the star.


\problem{Problem 4 (5 points)}
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Solve problem 17.4


\problem{Problem 5 bonus (5 points)}
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Calculate the time it takes a photon to travel from the Sun surface to
infinity applying the metric change due to gravity. Does your result mean
that the Sun is a black hole. Why so?


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