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Nova

Nova

The word nova, Latin for "new," was assigned by ancient astronomers to any bright star that suddenly appeared in the sky. A nova occurs when

one member of a binary star system temporarily becomes brighter. Most often the brighter star is a shrunken white dwarf, the cooling, shrunken core remaining after a medium-sized star (like our sun) ceases to burn. Its partner is a large star, such as a red giant, a medium-sized star in a late stage of its evolution, expanding and cooling.

As the companion star expands, it loses some of its mattermostly hydrogento the strong gravitational pull of the white dwarf. After a time, enough matter collects in a thin, dense, hot layer on the surface of the white dwarf to initiate nuclear fusion reactions. The hydrogen on the white dwarf's surface burns away, and while it does so, the white dwarf glows brightly. This is a nova. After reaching its peak brightness, it slowly fades over a period of days or weeks.

The transfer of matter does not stop after a nova explodes, but begins anew. The length of time between nova outbursts can range from several dozen to thousands of years, depending on how fast the companion star loses matter to the white dwarf.

A nova should not be confused with a supernova, which is the massive explosion of a relatively large star. A nova is much more common than a supernova, and it does not release nearly as much energy. Because novae (plural of nova) occur more often, they can change the way constellations in the night sky appear. For example, in December 1999, a bright, naked-eye nova appeared in the constellation Aquila, the Eagle. At its maximum, the nova was as bright as many of the stars in Aquila. For a few days at least, viewers were treated to the spectacle of a truly "new star" in an otherwise familiar constellation.

Words to Know

Binary star: Pair of stars in a single system that orbit each other, bound together by their mutual gravities.

Red giant: A medium-sized star in a late stage of its evolution. It is relatively cool and has a diameter that is perhaps 100 times its original size.

White dwarf: The cooling, shrunken core remaining after a medium-sized star ceases to burn.

[See also Binary star; Star; Supernova; White dwarf ]

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nova

no·va / ˈnōvə/ • n. (pl. -vae / -vē; -ˌvī/ or -vas ) Astron. a star showing a sudden large increase in brightness and then slowly returning to its original state over a few months. See also supernova.

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nova

nova (pl. novae) Faint star that undergoes unpredictable increases in brightness by several magnitudes, apparently due to explosions in its outer regions, and then slowly fades back to normal. See also variable star

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nova

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nova

nova A new star.

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nova

novaaquiver, downriver, forgiver, giver, quiver, river, shiver, sliver, upriver •silver • mitzvah • lawgiver • Oliver •miniver, Nineveh •quicksilver •conniver, contriver, diver, driver, fiver, Godiva, Ivor, jiver, Liver, reviver, saliva, skiver, striver, survivor, viva •skydiver • slave-driver • piledriver •screwdriver •bovver, hover •Moskva •revolver, solver •windhover •Canova, Casanova, clover, Dover, drover, Grsbover, Jehovah, left-over, Markova, Moldova, moreover, Navrátilová, nova, ova, over, Pavlova, rover, trover, up-and-over •layover • flyover • handover •changeover •makeover, takeover •walkover • spillover • pullover •Hanover • turnover • hangover •wingover • sleepover • slipover •popover, stopover •Passover • crossover • once-over •pushover • leftover

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