Introduction to Astrophysics II, 29:120
Spring, 2007
Tenth Homework Set...April 20, 2007. Due April 26, 2007

(1) The black hole in the Cygnus X-1 system has a mass of $10 M_{\odot}$ and an accretion rate (mass flow from the star into the accretion disk) of $1.8 \times 10^{-9} M_{\odot}$/year. Calculate the temperature of the accretion disk at a distance $r=15R_s$. In what part of the spectrum does this segment of the accretion disk radiate?

(2) A meter stick is moved into a point $2.8 R_s$ from the ``center'' of a $5 M_{\odot}$ black hole, and aligned in the radial direction. If we could measure its radial extent, what would it be?

(3) Derive the equation on p664 of the textbook (presented in class as a roundtrip propagation time).

(4) A radar transmitter on Earth bounces a signal off the planet Venus when it is at opposition. The line of sight passes by the Sun at a closest heliocentric distance (impact parameter $b$) of $b=3 R_{\odot}$. Compare the round-trip propagation time with that which occurs in the absence of the Sun. Is the difference measurable?

(5) Look at Table 1 in Remillard and McClintock, Annual Reviews of Astronomy and Astrophysics, vol 44, p49, 2006. Consider the case of 0422+32. The mass function is given as $1.19 M_{\odot}$, but the mass of the degenerate object is given as $3.7 - 5.0 M_{\odot}$. What factors must be accounted for to calculate the mass of the degenerate object?

(6) Problem # 16.17 from textbook

(7) Problem # 16.18

(8) Problem # 16.21