These were variously called "upper-class Novae", "Hauptnovae", or "giant novae". Observationally CEEs should be brighter than typical novae but fainter than typical supernovae. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. One of these extragalactic novae, M31N 2008-12a, erupts as frequently as once every 12 months. Recurrent novae (RNe) are objects that have been seen to experience multiple nova eruptions. The ten known galactic recurrent novae are listed below. Dwarf novae are dimmer and repeat more frequently than "classical" novae. All observed novae involve a white dwarf in a close binary system. The behavior of X-ray bursters is similar to the behavior of recurrent novae. The main sub-classes of novae are classical novae, recurrent novae (RNe), and dwarf novae. Lying near it is VW Hydri, one of the brightest dwarf novae in the heavens. These events are called luminous red novae (LRNe). Evolution of potential novae begins with two main sequence stars in a binary system. IM Normae is one of only ten recurrent novae known in the Milky Way. Since then, four other novae have been proposed as helium novae.