| 单词 |
quasar |
| 释义 |
quasar Astr.|ˈkweɪsɑː(r), -zɑː(r)|
[f. quasistellar a.]
Any of a class of celestial objects that give a star-like (i.e. unresolved) image on a photograph and have a spectrum showing a large red shift, usu. taken to indicate great remoteness and immense power.
1964H.-Y. Chiu in Physics Today May 21/2 So far, the clumsily long name ‘quasi-stellar radio sources’ is used to describe these objects. Because the nature of these objects is entirely unknown, it is hard to prepare a short, appropriate nomenclature for them so that their essential properties are obvious from their name. For convenience, the abbreviated form ‘quasar’ will be used throughout this paper. 1964Observer 14 June 1/1 For the past twelve months, astronomers have been obsessed with these ‘quasars’ or ‘quasi-stars’ as they are now called. 1968L. Durrell Tunc i. 18 Here was Vibart persuading poor Felix to quit quasars and debouch into memoirs. 1968Times 13 Nov. 16/2 One view is that the red-shift comes about because quasars are remarkably distant at the boundaries of the known universe. The other..is that quasars are extremely massive objects, and that the light from them is reddened by gravitational effects. 1971Sci. Amer. May 55/2 The term quasar..was originally applied only to the starlike counterparts of certain strong radio sources whose optical spectra exhibit red shifts much larger than those of galaxies. Before long, however, a class of quasi-stellar objects was discovered with large red shifts that have little or no emission at radio wave⁓lengths. ‘Quasar’ is now commonly applied to starlike objects with large red shifts regardless of their radio emissivity. Ibid. 56/2 Assuming that they are at cosmological distances, one can easily show that many quasars are from 50 to 100 times brighter than entire galaxies containing hundreds of billions of stars. 1973Nature 6 July 19/2 Two neutral-coloured stellar objects..have been shown to be QSOs with redshifts of 3·40 and 3·53 respectively. This has stimulated interest in other radio sources identified with stellar objects which lack the ultraviolet or blue colour excesses normally associated with quasars. 1978Daily Tel. 8 June 2/5 The nearest known quasar in space, an object the size of the solar system but emitting the energy of 100 galaxies, has been discovered by an X-ray experiment aboard an American satellite. 1978Pasachoff & Kutner University Astron. xxviii. 713 We now use the term quasar to include both quasi-stellar radio sources and quasi-stellar objects. |
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单词 quase 释义 ▪ I. quasvariant of kvass.▪ II. quas(eobs. northern forms of whose.{var ......