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super-hump





An additional modulation of the light curve of an SU Ursae Majoris stars caused by precession of the accretion disk. Super-humps show up in the light curve of a super-outburst as a modulation with a period a few percent longer than the orbital period. They continue until the star returns to quiescence, although their period usually drifts to slightly shorter periods and smaller amplitudes over time. Nicholas Vogt was the first to propose that super-humps were caused by the disk becoming elliptical during super-outburst. He suggested that such a disk would precess, meaning that the direction in which the disc was elongated would gradually rotate, on a timescale much longer than the orbit (in the same way, the axis of a spinning top precesses, but more slowly than it spins). The long precessional period of the disk would then interact with the orbital cycle to create a new periodicity – the super-hump.


Related category

   • STELLAR ASTROPHYSICS