The red giant is also continuously losing enormous amounts of gas in a wind that envelops the whole system. As a result, the explosion on the white dwarf occurs effectively inside its companion's atmosphere and the ejected gas then slams into it at very high speed.

RS Oph consists of a white dwarf, a dead star about the size of Earth in orbit around a much larger star, a so called red giant. Due to its proximity the white dwarf pulls hydrogen rich gas from the outer layers of the red giant and roughly every 20 years the build up of gas on the white dwarf’s surface causes a cataclysmic thermonuclear explosion. The rise to maximum brightness takes place in less than a day and at its height the energy output of RS Oph increases to over 100,000 times that of the Sun. The eruption ejects a quantity of material equivalent to the mass of the Earth at speeds of several thousand kilometers per second.