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supernovas, constellation Cygnus, star systems, novas, brightest star

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Nova, explosion on a star that makes the star increase rapidly in brightness. The star then slowly declines to its original level. Novas are members of a much larger class of binary, or double, star systems called cataclysmic variables. Early astronomers used the term nova (Latin nova stella, “new star”) to describe all astronomical objects that suddenly became visible to the naked eye. Astronomers now differentiate between novas and supernovas. Supernovas are very bright outbursts that radically change the original star.

A nova explosion is caused by the interaction of two stars that are close to each other. The gravitational pull of one star pulls off and drags the atmosphere of the other star onto its own surface. When the collected layer of atmosphere becomes thick enough, it explodes. After a nova outburst, the stars return to their original state relatively unchanged, and the system returns to its original brightness.

A nova outburst is one of the most dramatic events in astronomy. A nova appeared in the constellation Cygnus (the Swan) in 1975, rising to almost the brightness of Deneb (the brightest star in Cygnus). It stayed bright for about three days. While the brightness of most novas increases up to 1 million times that of the normal star, the brightness of this nova, called Nova Cygni 1975, increased at least 100 million times.


Starrfield, Sumner, B.A., M.A., Ph.D.

Professor of Astronomy, Arizona State University.

Article key phrases:

supernovas, constellation Cygnus, star systems, novas, brightest star, astronomical objects, original star, brightness, naked eye, days, astronomers, Swan, new star, astronomy, interaction, explosion, surface, stars, times, system, members

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