Wolf-Rayet Star

Wolf-rayet Star
Related Category: Astronomy: General
see spectral class.
More on Wolf-rayet Star
Spectral Class - in astronomy, a classification of the stars by their spectrum and luminosity. In 1885, E. C.

Wolf-Rayet stars (named for their discoverers) are very large, massive stars (stars which are about 20 times bigger than the sun) nearly at the end of their stellar lives.

Wolf-Rayet stars are very rare, we only know about 218 such stars in our own galaxy.

Wolf-Rayet star
Wolf-Rayet (W-R) stars are unusual stars that are very massive (over 40 times the mass of our Sun), extremely hot and very bright.

WOLF-RAYET STAR - Massive stars at an advanced stage of stellar evolution, losing mass at a very high rate (right). They have masses typically >25 Msun and brief lifetimes.

Wolf-Rayet stars. Stars that are very hot and are surrounded by an expanding gaseous envelope. They appear greenish-white in colour and their spectra show distinctive bright emmision lines.
X ...

Wolf-Rayet stars
are hot, blue giants. They are extremely turbulent and have a temperature of 50,000 °K and higher
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X-ray Astronomy
the field of astronomy that studies celestial objects by the x-rays they emit.

WOLF-RAYET STAR
A very hot, large star with apparent compositional peculiarities. The stars are losing mass very rapidly in the form of a high velocity stellar wind.

WOLF-RAYET STARS
Wolf-Rayet (W-R) stars are unusual stars that is very massive (over 40 times the mass of our Sun), extremely hot and very bright.

WR or Wolf-Rayet stars
Hot stars characterized by wide emission lines of highly ionized elements, standing out distinctly from the continuous spectrum. There exist three varieties: ...

WOLF-RAYET STARS
are unusual stars that is very massive (over 40 times the mass of our Sun), extremely hot and very bright.

Wolf-Rayet stars that are the central objects of a planetary nebulae. [JJ95] ...

Wolf-Rayet star - (n.)
A type of O star whose spectrum shows very broad emission lines.
W Virginis star - (n.) ...

A Wolf-Rayet star 17 times hotter than our Sun lies at the centre of Cygnus X-3. It is so hot that its mass wastes into space in a strong stellar wind.

A Wolf-Rayet star in NGC 2359. (Courtesy of the Anglo-Australian Observatory/Royal Observatory Edinburgh)
(70K GIF)
The Jewel Box cluster in Crux, NGC 4755. (Courtesy of the Anglo-Australian Observatory/Royal Observatory Edinburgh)
(49K GIF) ...

Many Wolf-Rayet stars, such as Gamma Velorum, WR 104, and those in the Quintuplet Cluster, are also considered possible precursor stars to a supernova explosion in the 'near' future.

Main article: Wolf-Rayet star
Artist's impression of a Wolf-Rayet star
Class W or WR represents the superluminous Wolf-Rayet stars, notably unusual since they have mostly helium in their atmospheres instead of hydrogen.

Wolf-Rayet stars (NASA Thesaurus) Very luminous, very hot (as high as 50,000K) stars whose spectra have broad emission lines (mainly He I and He II, which are presumed to originate from material ejected from the stars at very high velocities.

Gamma2 Velorum (and Wolf-Rayet stars in general).
Wolf-Rayets form a very rare type of star having extremely hot surfaces (perhaps up to 90,000 kelvin) and ejecting gas: WC eject predominately helium and carbon, WN nitrogen and helium, ...

Finally, a fifth type has been added, the Wolf-Rayet stars; these show a spectrum crossed by the usual dark lines and bands, but showing also bright emission bands of blue and yellow light.

27 mag and a bright (1.78 mag) Wolf-Rayet star. There are two wider companions of 9th and 10th magnitude; its a nice group for telescopes with small apertures.
To resolve the components of delta Vel scopes with apertures of at least 100 mm are needed.

Some exotic types of stars such as Wolf-Rayet stars exhibit strong, wide emission limes of ionised helium, carbon oxygen and nitrogen in their spectra. These rare, hot and extremely luminous stars are losing mass at a great rate.

This nebula originated from massive outflow from Wolf-Rayet star. It is also "surrounded" by larger more diffuse emission nebula. NGC6888 in Cygnus and NGC2359 in Canis Major are other examples of Wolf-Rayet nebulae.

In order: (1) the inner 10% core of a Wolf-Rayet star - an extremely massive class of bluish stars with a mass 10-15 times our sun's - this shows the iron, oxygen, and carbon shells; (2) due to a lack of fuel, ...

It is an emission nebula created by a fast stellar wind of a Wolf-Rayet star, an evolved, massive star showing strong emission lines of helium and nitrogen or helium, carbon and oxygen. It is approximately 5,000 light-years distant.

Related images (other sources)
AAT 16. NGC 2359, nebula around a Wolf-Rayet star In Canis Major.

Gamma Velorum is a blue supergiant and is the heaviest Wolf-Rayet star known.
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Mirfak, Algenib ...

and helium are present, and significant differences exist among certain isotopes. It is thought that the cosmic rays represent a mixture of interstellar material enriched with matter from evolved stars, such as supernovas and perhaps Wolf-Rayet stars.

These stellar winds are driven directly by the radiation pressure from photons escaping the star. In some cases, high-mass stars can eject virtually all of their outer envelopes in winds. The result is a Wolf-Rayet star.

Keck Observatory
Wolf 359
Wolf 1055 (Gliese 752, Ross 652)
Wolf-Lundmark-Melotte Galaxy (WLM Galaxy)
Wolf-Rayet star
Wollaston prism
wormhole
Wyoming Arizona Search for Planets
WZ Sagittae star ...

See also: Star, Light, Sun, Nebula, Emission