(4) The object Cygnus X-1 is extremely bright in X-rays, but invisible in optical telescopes. It appears to be very near a 40 solar mass star called HDE 226868, which shows a Doppler shift that oscillates with a 5.6 day period and maximum velocity \( 76 \mathrm{~km} / \mathrm{sec} \). Assuming that Cygnus X-1 and HDE 226868 execute circular orbits about their common center of mass, and that orbit is viewed edge on, find the mass of Cygnus X-1. There is evidence that the orbit is inclined at an angle of \( 30^{\circ} \) (instead of \( 90^{\circ} \) for edge-on). What is the mass in this case? What do you think Cygnus X-1 is? From time to time in this course, I will encourage you to look at journal articles regarding some subjects. In this case, you might look at one of the original "discovery" papers, namely Cygnus X-1 - a Spectroscopic Binary with a Heavy Companion?, by Louise Webster and Paul Murdin, Nature 235(07 January 1972)37.
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- Cygnus X-1 is near a 40 solar mass star, HDE 226868. - HDE 226868 shows a Doppler shift oscillating with a 5.6-day period and a maximum velocity of 76 km/sec. - We need to find the mass of Cygnus X-1 assuming circular orbits about their common center of mass. - Show more…
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