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This animation shows an artist's concept of Z Camelopardalis (Z Cam), a
stellar system featuring a collapsed, dead star, or white dwarf, and a
companion star. The white dwarf, the bright white object within the disk
on the left, sucks matter from its more sedate companion star, on the
right. The stolen material forms a rotating disk of gas and dust around
the white dwarf. After a certain amount of material accumulates, the star
erupts in a huge nova explosion, known as a "classical nova." After that
explosion, the star continues to flare up with smaller bursts, which is
why Z Cam is known today as a recurrent dwarf Nova. The remnants of the
classical nova explosion form a ghostly shell, which provides lingering
evidence of the violent outburst. The animation ends with an image taken
by NASA's Galaxy Evolution Explorer on Jan. 25, 2004, when the star system
was undergoing a period of relative calm.
Astronomers divide exploding binary star systems into two classes --
recurrent dwarf novae, which erupt in smaller, "hiccup-like" blasts, and
classical novae, which undergo huge explosions. A link between the two
types of novae had been predicted, but the observations from the Galaxy
Evolution Explorer bolster the theory that some binary systems undergo
both types of explosions.