mardi 23 septembre 2008

Pegasus 4

Pegasus, the winged horse, flew out of the head of Medusa when Perseus slew her. It was fathered by Poseidon, some time earlier, and waited for the Gorgon's death to appear. (Medusa's story is told under the constellation "Cepheus".)
Athene gave Pegasus to Bellerophon (a grandson of Sisyphus), who used the winged creature in his fight against the Chimaera - a monstrous female with three heads.
Bellerophon shot arrows at the beast as he flew above her on Pegasus, then he stuck between her jaws a huge lump of lead. The monster's own breath melted the lead, which then flowed down her throat and burned her to death. Now Bellerophon was sent off on another mission, which he accomplished with equal aplomb. Flushed with victory, he flew off for Olympus, home of the gods, as if he too were immortal. Zeus sent a gadfly, which stung Pegasus on the bum, and Bellerophon was kicked off the horse.
Pegasus went alone to Olympus, where he was used by Zeus to carry around his thunderbolts. As for Bellerophon, for his presumption of greatness, he wandered about the earth for the rest of his life, blind, lame, and shunned by man, until dying of old age.

Is a conspicuous constellation which includes the so-called "Great Square of Pegasus". However it must now share the northeast corner of the square with Andromeda: delta Pegasus was given to Andromeda, to provide the lady with a head!
The stars are generally second and third magnitude. There are several interesting binaries here, a curious flare star, and one outstanding deep sky object.

Double stars in Pegasus:
Kappa Pegasi is a very close binary, with an orbit of only 11.52 years: 4.8, 5.3; presently the companion is at PA 132 degrees and separation of only 0.2".
37 Pegasi is another close binary, with an orbit of 140 years: 5.8, 7.1; presently the companion is found at PA 118 degrees and separation of 0.8".
85 Pegasi is a well-known close binary with orbit of 26.27 years: 5.8, 8.9; currently the companion is at PA 149 degrees and separation of 0.8".

Variable stars in Pegasus:
Epsilon Pegasi is an irregular (Lb type) variable, and a flare star with a relatively cool shell. This supergiant can get as bright as 0.7 magnitude, and dimmer than 3.5. Generally it stays around 2.4.

Deep Sky Objects in Pegasus:
Pegasus has many galaxies and an outstanding globular cluster.
M15 (NGC 7078) is one of the finest globular clusters in the heavens, very bright and compact, at 35,000 to 40,000 light years away. It is found four degrees NW of epsilon Pegasi.
NGC 7331 is a spiral galaxy resembling the Milky Way Galaxy; it's as if we were looking at outselves from fifty million light years away.
NGC 7479 is a barred spiral galaxy about three degrees due south of alpha Pegasi.
Stephan's Quintet is a noted cluster of galaxies half a degree SSW of NGC 7331. See how many of the five you can spot (three is average, four is good).

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