单词 | recurrent nova |
释义 | recurrent novarecurrent nova(ri-ku -rĕnt, -ker -ĕnt) A cataclysmic variable that suffers a series of violent nova?-like outbursts at periodic intervals. The change in brightness is smaller and the decline in brightness more pronounced than with classical novae. Like other cataclysmic variables, a recurrent nova is a close binary system in which one member is a white dwarf; the other component is a red giant, and gas is being transferred from the latter to the former. The red giant loses matter about a thousand times faster than the companion in a nova system, so that the transferred hydrogen builds up on the surface of the white dwarf at a much quicker rate. The accumulated hydrogen is hence sufficient to erupt in a thermonuclear explosion after only a few decades, and astronomers have been able to see multiple outbursts within the past century or so of systematic investigation of variable stars. Between outbursts, the system's light comprises both emission from hot gas circling the white dwarf and light from the cool red giant; as a result the spectrum shows what is apparently a star with two different temperatures (as with a symbiotic star). T Pyxidis (1890, 1902, 1920, 1944, 1965), RS Ophiuchi (1901, 1933, 1958, 1967, 1985), T Coronae Borealis (1866, 1946), U Scorpii (1863, 1906, 1936, 1979, 1987), and V394 Coronae Australis (1949, 1987) are recurrent novae.recurrent nova[ri′kər·ənt ′nō·və] |
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