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 ?
Zeta Puppis likely became a solitary supergiant due to past interaction with a binary or multiple system.
They reason that a new, currently unknown, process may be needed to explain these movements in the extended atmospheres of red supergiants like Antares.
Both of these are supergiants putting out more than 20,000 times as much light as our Sun and 12 million times as much light as Proxima Centauri.
At this point, the gravitational force of the red supergiant is balanced by its tremendous outward radiation pressure that is derived from the frantic fusion of the helium in its core.
Thanks in part to observations by the International Ultraviolet Explorer (IUE) satellite, it was soon established that the progenitor star was the blue supergiant, Sanduleak -69[degrees] 202.
The dying red supergiant Betelgeuse, though, might better have been named "Ginormous.
It is thought to be the biggest whole specimen of a supergiant ever caught.
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.
Bansko thus becomes one of only five locations that will host both men's and women's World Cup events in the same season: men's slalom and giant slalom on February 18-19 2012, followed by women's downhill and supergiant slalom on February 25-26.
Royal Dutch Shell may build its own dock in Iraq's Shatt al-Arab waterway to speed up delivery of heavy equipment to the supergiant Majnoon oilfield which the oil major is developing with a Malaysian partner.
LN), a Nethersland-based oil and gas company, is planning to raise oil production from Iraq's supergiant Majnoon oil field, Dow Jones has reported, citing a company executive.
Last month Oil Minister Hussain al-Shahristani said the contract would not include the supergiant 12.