http://apod.nasa.gov/apod/ap130816.html
http://asterisk.apod.com/viewtopic.php?f=29&t=31928
Using a small telescope to scan the skies on August 14, Japanese amateur astronomer Koichi Itagaki discovered a “new” star within the boundaries of the constellation Delphinus.
The nova is reported to be easy to spot with binoculars, near the limit of naked-eye visibility under dark skies. In fact, previous deep sky charts do show a much fainter known star (about 17th magnitude) at the position of Nova Delphini, indicating this star’s apparent brightness suddenly increased over 25,000 times.
How does a star undergo such a cataclysmic change? The spectrum of Nova Delphini indicates it is a classical nova, an interacting binary star system in which one star is a dense, hot white dwarf. Material from a cool, giant companion star falls onto the surface of the white dwarf, building up until it triggers a thermonuclear event. The drastic increase in brightness and an expanding shell of debris is the result – but the stars are not destroyed! Classical novae are believed to recur when the flow of material onto the white dwarf resumes and produces another outburst.