(a) 0.0079 km/sec is very slow compared to the speed of light, so we can use the
non-relativistic version of the Doppler equation:

    delta(lambda)    v
    ------------- = ---  where c = 3 * 10^5 km/s.
      (lambda)       c

So, since (lambda) = 656.3 nm, we can compute

     delta(lambda) = (656.3 nm) * (0.0079 km/s)/(3 * 10^5 km/s)
                   = 0.000017 nm

Physically, this length is about one ten-thousandth the diameter of a hydrogen
atom in its lowest energy state.

(b) According to the Doppler equation, delta(lambda)/(lambda) for the Sun-Jupiter
system would be  v/c = (0.0079 km/s) / (3 * 10^5 km/s) = 2.6 * 10^(-8). 
The spectrograph has a delta(lambda)/(lambda) = 0.000001 or 1.0 * 10^(-6).
Unfortunately, this spectrograph would not come close to detecting Jupiter's
Effect on the motion of the Sun's center of mass.

(c) If Jupiter were ten times more massive, then the center of mass of the Sun-
Jupiter system would be 105 times farther away from Jupiter than from the Sun.
The average speed of the center of mass would then increase by ten times. (These 
values come from the reasoning in Exercise 1, Part (a), and is left as an exercise 
to the reader.)  The fraction (v/c) would also increase by ten times, to a value 
of 2.6 * 10^(-7).  This is one-fourth the limit of detection by the super-high
resolution spectrographs mentioned in Part (b) of this exercise, so it might be 
close to detectable.

(d) If Jupiter were one AU away from the Sun, it would take only six months to 
pull the center of mass from far side to near side.  The distance traveled by the 
center of mass, however, would be 5.2 times shorter.  So the velocity would 
increase by a factor of about 2.3 (again, these steps of reasoning are left as
an exercise for the reader).  Now the fraction (v/c) would be, for the bulked-up
Jupiter, about 6.0 * 10^(-7), which is quite close to detectable by the super
high-resolution spectrograph described in Part (b) of this exercise.  

NOTE: Parts (c) and (d) show how the cutting edge of exoplanet discovery could
advance in the coming years.  As astronomical spectrographs improve, planets with 
masses and orbits resembling those in our own solar system move within reach of 
discovery.