supergiant


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Related to supergiant: Red supergiant, Blue supergiant

supergiant

(soo -per-jÿ-ănt) The largest and most luminous type of star, lying above both the main sequence and the giant region in the Hertzsprung–Russell diagram. They are grouped in luminosity classes Ia and Ib (see spectral types) and generally have absolute bolometric magnitudes between –5 and –12. Only the most massive stars can become supergiants and consequently they are very rare. They are so bright, however, that they stand out in external galaxies. There is an upper limit to the absolute bolometric magnitude of cool red supergiants (–9.7), so the brightest supergiants can be used as approximate distance indicators. Examples of supergiant stars are Rigel and Betelgeuse in Orion, Antares in Scorpius, and Cepheid variable stars. See also luminous blue variables.

Supergiant

 

in astronomy, a massive star of the highest luminosity. The absolute stellar magnitudes of supergiants reach values of - 7 and - 8. Supergiants include stars of various spectral classes. The diameters of cool (red) supergiants, such as Betelgeuse or the red component of VV Cephei, are hundreds or thousands of times greater than the diameter of the sun. The diameters of hot supergiants, such as Rigel, exceed the diameter of the sun by a factor of 20 to 30. The total fraction of supergiants among all the stars is small. Supergiants occur in stellar associations and in younger open clusters; they often are components of binary systems. Observations indicate an escape of matter from the surface of many supergiants as well as other signs of instability. All such phenomena make the supergiants particularly important for the development of a theory of stellar evolution.

References in periodicals archive ?
Most known runaway stars are in the Milky Way; this yellow supergiant is only the second known evolved runaway in another galaxy.
The B-type blue supergiant star, hundreds or even thousands of times brighter than the sun, was discovered in Hubble Space Telescope images taken over the course of a year between April 2016 and 2017.
A second shock wave ripples through the star--just powerful enough to burp off the loosely held outer layers of the supergiant and expose the feeding black hole.
The last supernova discovered by NASA specialists was in 2011, when two red supergiants exploded which was viewed through Kepler, according to NASA's bulletin.
It is not clear whether the operation was in response to Eni's announcement of a "supergiant" gas field in the Mediterranean Sea, off the coast of Egypt, on Sunday.
We briefly discuss three blue supergiant (BSG) properties that are or could be relevant for the sgB[e]: evolutionary phase indicators, rotational velocities, and evidence for dust production.
Betelgeuse is the nearest red supergiant star to Earth, as well as the best known.
A blue supergiant has a much smaller radius than a red supergiant.
The belt, which looks like three simple kindred stars cinching the midsection, actually consists of a two-star system, a distant blue supergiant, and a triple star - lined up from our vantage point just by chance.
"Supergiant amphipods" have been found just once before, in the 1980s.
The "supergiant" species is a type of amphipod, which are usually just 0.8-1.2in.
Thamer Ghadhban said some $50 billion would be spent to upgrade the supergiant West Qurna Phase 1 oil field which is being developed by Exxon Mobil.