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

Question

Quizplus · Accepted Answer

The emission of X-rays characteristic of an accretion disk indicates the presence of a compact object with a strong gravitational pull, and the fact that the unseen star in the system is too massive to be a neutron star suggests that it must be a black hole. Options A and B are not necessarily true as other phenomena can also generate strong X-ray emissions, and Option C is not true as not all black holes are completely dark.

What Makes Us Think That the Star System Cygnus X-