(a) Using the observed characteristics of Star S2's orbit as given in the preceding problem, and assuming it moves in a Keplerian elliptical orbit, find the speed of the star at periastron as a percentage of the speed of light.

(b) If its orbit happened to be oriented so that at periastron S2 were moving directly towards the earth, by what factor would its light be blue-shifted due to the Doppler effect?