Figure: In a semidetached binary system, gas from one star can
overflow its Roche lobe and fall into a disk orbiting the other star.
This is known as an accretion disk.
A disk of gas which accumulates around a center of gravitational attraction, such as a white dwarf, neutron star, or black hole. As the gas spirals in, it becomes hot and emits light or even X-radiation.
Figure: In a semidetached binary system, gas from one star can
overflow its Roche lobe and fall into a disk orbiting the other star.
This is known as an accretion disk.