What makes us think that the star system Cygnus X-1 contains a black hole?
A)It emits X-rays characteristic of an accretion disk,but the unseen star in the system is too massive to be a neutron star.
B)No light is emitted from this star system,so it must contain a black hole.
C)The fact that we see strong X-ray emission tells us that the system must contain a black hole.
D)Cygnus X-1 is a powerful X-ray burster,so it must contain a black hole.

Question

Quizplus · Accepted Answer

The star system emits X-rays that are characteristic of an accretion disk, but the unseen star in the system is too massive to be a neutron star. This suggests that the system contains a black hole, which would be the only other object massive enough to create such a gravitational pull.

What Makes Us Think That the Star System Cygnus X-1