Z Camelopardalis star
The prototype system, Z Camelopardalis, lies about 530 light years from Earth and was the first dwarf nova ever detected. It consists of a G-type (Sun-like) dwarf and a white dwarf or a blue subdwarf that orbit around each other every 7h 21m; eruptions occur on average every 20 days.
Theory predicts that the white dwarfs in all dwarf novae must eventually accrete enough mass to undergo classical nova eruptions, but no dwarf nova has ever been shown to have undergone a classical nova eruption – with the exception of Z Cam. In a Letter to the Editor, published in Nature in July 2007, Göran Johansson, of the University of Lund, Sweden, pointed out that an eruption of Z Cam had been recorded by the Chinese in 77 BC.1
Observations by the NASA ultraviolet satellite GALEX have revealed the shell of Z Camelopardalis. This shell is about 10 times more extended than any detected around any classical nova. The derived shell mass matches that of classical novae, and is inconsistent with the mass expected from a steady dwarf nova wind. Thus the shell mass and morphology observationally link, for the first time, a dwarf nova with the classical nova process, just as theory predicts.
Related entries UX Ursae Majoris star
Related category• TYPES OF STARS
Home • About • Copyright © The Worlds of David Darling • Encyclopedia of Alternative Energy • Contact