Z Andromedae is a binary star system consisting of a red giant and a white dwarf. It is the prototype of a type of cataclysmic variable star known as symbiotic variable stars or simply Z Andromedae variables. The brightness of those stars vary over time, showing a quiescent, more stable phase and then an active one with a more pronounced variability and stronger brightening and/or dimming. Binary system Z Andromedae is a binary star system. The two components have a circular orbit that takes 759 days to complete. The red giant is around twice the mass of the sun and 880 times its luminosity, but its effective temperature is only 2,800 K. The white dwarf is around a thousand times the luminosity of the sun during the quiescent phase, but up to 10 times more luminous during the active phases. Its temperature is as high as 150,000 K when quiescent, but drops below 100,000 K when active. It also spins around its rotation axis every 1,682 seconds and displays a strong magnetic field. The evolved red giant star is losing mass, since radiation pressure overcomes the low gravity on the surface. The outflow of matter is captured by the gravitational field of the white dwarf and falls on its surface in the end. At least during the active phase an accretion disk forms around the white dwarf. Variability During the quiescent phase, most of the white dwarf luminosity comes from stable hydrogen burning on its surface, and photons emitted this way ionize the wind of the red giant which causes nebular emission. The giant star, however, follows a quasi-periodic activity cycle (similar to the solar cycle) roughly every 7,550 days; when the activity of the star is enhanced, the stellar wind becomes stronger, and in response the white dwarf increases in size and cools, triggering the active phase. In the quiescent phase, the brightness of Z Andromedae is modulated by the orbital period of the system, and can reach a magnitude of mv = 11.3 at minimum. During the active phase Z Andromedae makes luminosity outbursts and can increase its brightness up to a magnitude of mv = 7.7. Eclipses from the red giant are still visible in this phase. During this phase, a shorter periodicity of 685 days is observed; this could be a beat period between the unknown rotation period of the giant star and the orbital period,