| 单词 | supernova |
| 释义 | supernova[ soo-per-noh-vuh ] / ˌsu pərˈnoʊ və / SEE SYNONYMS FOR supernova ON THESAURUS.COM noun, plural su·per·no·vas, su·per·no·vae [soo-per-noh-vee]. /ˌsu pərˈnoʊ vi/. Astronomy.the explosion of a star, possibly caused by gravitational collapse, during which the star's luminosity increases by as much as 20 magnitudes and most of the star's mass is blown away at very high velocity, sometimes leaving behind an extremely dense core. the star undergoing such an explosion. Compare supernova remnant, black hole, neutron star, nova. Origin of supernovaFirst recorded in 1925–30; super- + nova Words nearby supernovasupernatural, supernaturalism, supernaturality, supernaturalize, supernormal, supernova, supernova remnant, supernumerary, supernurse, supernutrient, superolateral Dictionary.com UnabridgedBased on the Random House Unabridged Dictionary, © Random House, Inc. 2020 Example sentences from the Web for supernovaBritish Dictionary definitions for supernovasupernova / (ˌsuːpəˈnəʊvə) / noun plural -vae (-viː) or -vasa star that explodes catastrophically owing to either instabilities following the exhaustion of its nuclear fuel or gravitational collapse following the accretion of matter from an orbiting companion star, becoming for a few days up to one hundred million times brighter than the sun. The expanding shell of debris (the supernova remnant) creates a nebula that radiates radio waves, X-rays, and light, for hundreds or thousands of yearsCompare nova Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Cultural definitions for supernovasupernova [ (sooh-puhr-noh-vuh) ] A large star in its death throes that suddenly explodes, increasing many thousands of times in brightness. notes for supernovaMost heavy elements are created by nuclear reactions in supernovas and then returned to space. notes for supernovaIn 1987, a supernova was sighted near the Milky Way galaxy. This supernova provided astronomers with a unique opportunity to test the theories of the structure of stars. The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved. Scientific definitions for supernovasupernova [ sōō′pər-nō′və ] Plural supernovae (sōō′pər-nō′vē) supernovasA massive star that undergoes a sudden, extreme increase in brightness across the electromagnetic spectrum, followed by a more gradual decrease lasting from several days to several months. Supernovae occur when a supergiant star collapses suddenly at the end of its life, condensing its core material into an extremely compact mass that then undergoes a slight rebound. The resulting shock wave sends all matter surrounding the core flying into space, leaving a neutron star or black hole at the site of the core's collapse. Supernovae may also occur when a white dwarf accretes material from a companion red giant star, resulting in an increase in mass that eventually triggers carbon fusion in the core of the white dwarf; the sudden increase in available fuel causes energy to be released in a violent explosion. In both cases the shock waves induce further fusion in the matter surrounding the collapsed core; the many elements resulting from this fusion and from the various other stages of nucleosynthesis over the lifetime of the star are scattered into space. These elements serve as the material from which new stellar and planetary systems are formed; in fact, every heavy element found on Earth is thought to have been the product of supernovae explosions. The last supernova to be observed in the Milky Way was seen in 1604 by Johannes Kepler and was used by Galileo, at his trial, as evidence against the presupposition that the universe never changes. Compare nova. The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved. |
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