This friction will heat up the gas, and also slow the gas down, so that it gradually spirals in towards the white dwarf. The gas will form an accretion disk. If a secondary star is accreting onto a compact object, such as a white dwarf, the orbital speed and friction can be extremely high. Finally, let's consider some of the strange objects that are formed by accreting systems. First, let's accrete onto a normal white dwarf.
White dwarfs are white dwarfs because they have no hydrogen to burn.
However, through accretion, the star can find itself with a substantial layer of hydrogen on its surface. We call this a nova. Now, let's fast forward a few years. White dwarfs are white dwarfs because electron degeneracy holds up the star against gravity. But electron degeneracy only works if the star is less than 1.4 solar masses.