White dwarf observed before and after going nova

BBC : In close binary star systems, a white dwarf accretes matter from its companion star until an explosion, called a nova, occurs; the phenomenon repeats over periods of thousands of years. For the first time, such a system has been observed not only as it exploded but for several years before. The images were captured as part of the Optical Gravitational Lensing Experiment, a long-running sky survey to look for dark matter. After the white dwarf went nova, Przemek Mróz of the University of Warsaw Astronomical Observatory and colleagues looked back at the images they had captured and noted that the rate of mass transfer between the stars was much higher and stabler after the explosion than it was before it. The observation supports the researchers’ theory that classical novae undergo a cyclical process whereby a period of high mass transfer is followed by a period of hibernation, when the white dwarf ceases to steal gas from its partner and the system goes almost completely dark.