Education Activities To Accompany Chandra Data Analysis Software Cen X-3 & Clocks in the Sky
Interpreting the power spectrum: how fast is the pulsar moving?
Other observations show a remarkable feature. Every 2.1 days the x-rays
disappear for about 12 hours. When the x-rays reappear, the pulses
reach us at higher frequencies (eventually reaching a frequency of
0.2083 pulses per second); 1.05 days (half the orbit period) later, the
pulses start reaching us at lower frequencies (eventually dropping to a
frequency of 0.20783 pulses per second). This oscillation in the pulse
frequency continues, back and forth, every 2.1 days. What we are
apparently seeing is the x-ray source moving towards us (giving us a
higher frequency Doppler shift) and then moving away from us, on the
other side of the orbit (giving us lower frequencies). Our clock is
telling us about the nature of the orbit of the x-ray source! The exact
way the frequencies change tells us that the orbit is essentially a
circular one, with the x-ray source moving rapidly about another
object. How fast? We use the Doppler shift formula to find out:
Click Here for the Solution Click Here for Detailed Hints
