The irregular variability of this star was discovered by L. Meinunger in 1975.[8][9] The spectra was found to resemble a blue–hued OB star with some peculiarities. It is a confirmed cataclysmic variable (CV) but its properties differ markedly from other sub-classes of that type.[10] The photometric behavior of the star is dissimilar to that of a dwarf or polar nova as it shows rapid brightening of up to three magnitudes in periods of around a day,[11] but stays in a low excitement state about 72% of the time.[10] Evidence for weak emission of the hydrogen–alpha line was discovered by W. Liu and associates in 1999.[9]
This is a close binary system with an orbital period of 223 minutes (3.7 hours). The primary component is a white dwarf star with 75% of the mass of the Sun. The secondary component has 27% of the Sun's mass and is overflowing its Roche lobe, resulting in mass transfer to an accretion disk orbiting the primary. The accretion rate for the primary is 3×10−9M☉·yr−1.[5]
T. Kato and associates in 2003 found the light curve matched a Z Cam variable, with the previously observed inactive states being caused by a characteristic standstill. The duty cycle of its standstill is unusually long for a variable of this class.[10] Outbursts during these standstills may be explained by flares on the secondary, which result in brief surges in mass transfer.[12]
^Meinunger, L. (May 1980), "Spectra of Four Blue Irregular Variables in Andromeda", Information Bulletin on Variable Stars, 1795: 1, Bibcode:1980IBVS.1795....1M.
^Meinunger, L.; Andronov, I. L. (September 1987), "Photometric Study of the Blue Variables IW, IZ and IO Andromedae", Information Bulletin on Variable Stars, 3081: 1, Bibcode:1987IBVS.3081....1M.
^Kato, Taichi; Kojiguchi, Naoto (December 2020), "BC Cassiopeiae: First detection of IW Andromedae-type phenomenon among post-eruption novae", Publications of the Astronomical Society of Japan, 72 (6): 98, arXiv:2009.12993, Bibcode:2020PASJ...72...98K, doi:10.1093/pasj/psaa096, 98.
