Eruptive variable stars vary in brightness because of the violent progresses such as flares that occur on the surface of the star. The changes in luminosity coincide with shell events or mass outflow in the form of stellar wind, or interaction with outside interstellar medium. Again, there are different types of eruptive stars which have different kinds of light-curves such as:
Orion variables of the FU Orionis type can be characterised by their gradual increase in brightness (of about 6 magnitudes) over several months which is followed by either complete constancy of the maximum brightness sustained over long periods of time, or slow decline (by 1-2 magnitudes).V1515 Cyg Or for another example of a V1515 Cyg light curve click here.
R Coronae Borealis type variables are high luminosity stars, which are simultaneously pulsating and eruptive variables. They show slow non-periodic fading which ranges from about a month to several hundred days. These eruptive changes are superposed on cyclic pulsations, with periods in the range of 30-100 days. RCB stars should have light-curves that show variation in the luminosity of the star when it erupts or pulsates.V504 Cen
UV Ceti type variables sometimes show flare activity. The star's brightness is greatest several seconds after a flare. The star then returns to its normal brightness minutes later.DF Cnc
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