Wolf-Rayet star


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Wolf-Rayet star:

see spectral classspectral class,
in astronomy, a classification of the stars by their spectrum and luminosity. In 1885, E. C. Pickering began the first extensive attempt to classify the stars spectroscopically.
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Wolf-Rayet star

[¦vȯlf rī¦ā ‚stär]
(astronomy)
A member of a class of very hot stars (100,000-35,000 K) which characteristically show broad bright emission lines in their spectra; luminosities are high, probably in the range 104-105 times that of the sun; these stars are probably very young and represent an early short-lived stage in stellar evolution.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
In that process, the more compact star winds up gaining mass, and the original massive star loses its hydrogen envelope, exposing its helium core to become a Wolf-Rayet star.
Wolf-Rayet stars provided a possible answer because they released a lot of aluminum-26 but no iron-60.
"Thick winds continually poured off the progenitors of such stars, flooding their surroundings and draining the outer layers of the Wolf-Rayet stars," NASA said.
Wolf-Rayet stars are near the end of their lives and expel most of their outer layers into their surroundings before exploding as supernovae, with their cores imploding to form black holes.
Most Wolf-Rayet stars either aren't hot enough or don't have enough gas surrounding them to produce bright, easy to see Hell nebulas, notes Claus Leitherer of the Space Telescope Science Institute in Baltimore.
"In just 100,000 years, this fast, dense wind removes as much mass from the Wolf-Rayet star as our Sun contains," said Robin Corbet at the University of Maryland, Baltimore County.
It is losing mass rapidly through powerful stellar winds that have expelled the majority of its outermost hydrogen-rich layers, while its more mundane binary companion is probably about half as massive as the Wolf-Rayet star, and orbits around it once every 208 days.
Drissen's team speculated that the winds blown either by bright, hot stars known as Wolf-Rayet stars or by old stars called red supergiants could have pumped up the gas.
Three 11th-magnitude stars lie along the north portion of the rim, and the 11.4-magnitude Wolf-Rayet star HD 56925 is just northwest of center.
Its companion also soon becomes a Wolf-Rayet star and then undergoes a supernova explosion.
In 1996 a Belgian team led by Gregor Rauw studied the very massive Wolf-Rayet star WR22 and measured a minimum mass of 72 Suns.
Large instruments reveal the object's bubble-like structure, which is due to fast stellar winds of a Wolf-Rayet star colliding with the surrounding interstellar medium of gas and dust pervading the region.