mardi 23 septembre 2008

Pegasus 5

Epsilon Pegasi (ε Peg / ε Pegasi) is a star in the constellation Pegasus. It also has the traditional name Enif.
It is fairly average for an orange supergiant star, well into the later stages of its stellar evolution and as such may be considered a dying star. Enif likely only has a few million years left to go, although it is unknown whether it will explode in a supernova or die off as a rare neon-oxygen white dwarf, due to its mass straddling the dividing line between stars destined to explode or not. Enif has been observed to brighten radically upon a few occasions, giving rise to the theory that it (and possibly other supergiants) erupt in massive flares that dwarf those of our own Sun.
The word Enif is derived from the Arabic word for nose, due to its position as the muzzle of Pegasus.
The nose

Beta Pegasi (β Peg / β Pegasi) is a star in the constellation Pegasus. Its traditional name is Scheat; confusingly, this name is also sometimes used for Delta Aquarii.
Scheat is unusual among bright stars in having a relatively cool surface temperature (3700 kelvins) compared to stars such as the Sun. Scheat is a red giant some 95 times as large as the Sun and has a total luminosity of 1500 times solar. It is also an irregular variable star, its brightness varying from magnitude +2.31 to +2.74.

Alpha Pegasi (α Peg / α Pegasi) is the third brightest star in the constellation Pegasus (despite its "alpha" designation) and one of the four stars in the asterism known as the Great Square of Pegasus. It also has the traditional name Markab (or Marchab).
Markab is a relatively average star nearing the end of its stellar evolution on the main sequence. Markab will soon enter the helium burning phase of its development, during which it will likely expand into a red giant. Like the Sun, it will probably end its life quietly as a white dwarf.
The name Markab comes from an Arabic word مركب markab, "the saddle of the horse", or is mistranscription of Mankib comes from an Arabic phrase منكب الفرس Mankib al-Faras, "(the Star of) the Shoulder (of the Constellation) of the Horse" for β Pegasi.

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