Self-study
A ring of gas emitting X-rays flickering 450 times per second has been observed in a stable orbit around a black hole. ██ █████ ██ ███████ ██████ ████████ ████████ █████████ ████ ████ ██ ██████████ ███ ████ ██ █████████ ██ ███ ████ ██ ███ ███ █ ██████ ██ ██ ███████████ ███ ███ ███ ████ █████ ███ ████████ ██ █████ ██ █████ ██ █ █████ ████ ██████ ███ █████ ████ ███ █████████
Summary
Scientists have seen a ring of gas that maintains a stable orbit around a black hole. The gas ring emits X-rays that flicker 450 times per second. This flickering speed suggests that the gas ring has a radius of 49 kilometers, meaning that it is very close to the black hole. However, for the gas ring to maintain its orbit so close to the black hole, the black hole itself must be spinning.
Strongly Supported Conclusions
In some conditions, gas can orbit black holes at a close distance.
The black hole is spinning.
10.
The statements above, if true, ████ ████████ ███████ █████ ███ ██ ███ ██████████ ████████ ████ ███ ██████ ████████ ████████ ████████ ████████ ██ █████ ███ ████████
a
Black holes that ████ ████████ █████ ██ ███ ████ █████ ███████ ████ ██ ██████████ ███ ███████ ███████████
This is unsupported. We know only that black holes that have orbiting rings of gas with radii of 49 kilometers must be spinning. We do not know the conditions of black holes that have orbiting rings of gas with radii greater than 49 kilometers.
b
Only rings of ███ ████ ███ ██ ██████ ██████ ██████ █████ █████ ████ ██████████ ███████
This is unsupported. The stimulus only tells us about this particular ring of gas. We do not have any information about the emissions of any other rings of gas.
c
The black hole ████ ██ ██████ ███ ████ ██ ███ ████████ ██ ███ ███████████ ██ █████████
This is strongly supported. We know that the gas ring has been observed in a stable orbit very close to the black hole. Because the ring can only maintain such a close orbit if the black hole is spinning, we can conclude that the black hole is spinning.
d
X-rays emitted by █████ ██ ███ ████████ █████ █████ █████ █████ █████ █████ ██ █████
This is unsupported. The stimulus tells us that the black hole must be spinning based on the observed facts of the gas ring. However, it does not tell us what causes the black hole to spin.
e
A black hole ██ ██████████ ████ ██ ██ ██ ███████ ██ █ ████ ██ ███ ████ █ ██████ ██ ████ ████ ██ ███████████
This is unsupported. We know only that a black hole orbited by a gas ring with a radius of 49 kilometers must not be stationary. We do not know the conditions required for a black hole to be stationary.