Pegasus (constellation)

Pegasus is a northern constellation, named after the mythological Pegasus. It is one of the 88 modern constellations, and was also one of the 48 constellations listed by Ptolemy.

Notable features

αPeg (Markab), βPeg, and γPeg, together with Alpha Andromedae (Alpheratz or Sirrah) form the large asterism known as the Square of Pegasus. A star in this constellation, 51 Pegasi, is orbited by the first true extrasolar planet (planets orbiting a star other than the Sun) to have been discovered.

Notable deep sky objects

M15 - a globular cluster near the head (ε Peg) of Pegasus.
NGC 7742 - a Type 2 Seyfert galaxy.

History and mythology

Pegasus has an appearance resembling a grazing horse, with a large square area as its body ^*. Due to the presence of the 4 brightest stars in the square, i.e. the 4 horses of pegasus, this may be part of the origin of the myth of the Mares of Diomedes, one of The Twelve Labours of Herakles, together with another feature in the Zodiac sign of Aquarius, namely Aquarius itself, pouring out the waters.

The star Delta Pegasi (labeled "Sirrah" in the map), one of the 4 stars in Pegasus' square, is now considered to be part of Andromeda, (α Andromedae) and is more usually called "Alpheratz." By moving the star, the square became a triangle attached to a stick body, thus resembling a wing. As a winged horse, Pegasus features in Greek mythology as its namesake, Pegasus.

Popular culture

Pegasus was one of four constellations depicted in a United States Postal Service commemorative stamp issue of October 2005 entitled "Constellations". (05_constellations37_f.jpg)

Visualization

Among Pegasus' brightest stars (of the second magnitude) are α Peg and β Peg, which together with γ Peg (third magnitude) form the triangular wing of the horse.

The body of the horse consists of a quadrilateral formed by the stars α Peg, λ Peg, ι Peg, and ξ Peg.

The front legs of the winged horse have two stars of the fourth magnitude which have no Bayer designations but which do have Flamsteed numbers: 1 Pegasi and 9 Pegasi.

The stars ε Peg and θ Peg belong to the hind legs, with ε being of the third magnitude. ρ Peg and σ Peg belong to the tail, but they are both dim: of the fifth magnitude.

η Peg and π Peg form the head: π is the snout, and η has magnitude three. μ Peg is the beginning of the neck.

Reference

H. A. Rey, The Stars — A New Way To See Them. Enlarged World-Wide Edition. Houghton Mifflin, Boston, 1997. ISBN 0-395-24830-2.

Stars

Stars with proper names:

(54/α Peg) 2.49 Markab or Menkib al Faras [Matn al Faras
< مركب markab vehicle boat, etc.
< منكب الفرس minkabal-faras [The shoulder of the horse
< متن الفرس matnal-faras [The body of the horse

(53/β Peg) 2.42 Scheat Seat Alpheras (or Menkib, see ξ Per)
< ? as-sa'id al-faras The upper arm of the horse

(88/γ Peg) 2.83 Algenib
< الجنب al-janb the flank
or < الجانبal-jānib the flank

δ Peg: moved to Andromeda as α And

(8/ε Peg) 2.38 Enif Enir, Al Anf or Fom al Faras or Os Pegasi
< الأنف al-´anf nose
< الفم الفرس al-fum al-faras The mouth of the horse
< ōs pēgasi The mouth of Pegasus, < πήγασος

(42/ζ Peg) 3.41 Homam Humam, Al Hammam
< سعد الهمام sa^{c^dal-humām} the high-minded [man

(44/η Peg) 2.93 Matar al Matar
< سعد المطر sa^{c^{d^* al-maţar}} Luck of the rain

(26/θ Peg) 3.53 Baham Sad al Baham
< سعد البهايم sa^{c^{d^* al-bahāyam}} Luck of the livestock

(48/μ Peg) 3.51 Sadalbari al Bari or Sad al Nazi
< سعد البري sa^{c^{d al-bariyy}} Luck of the guiltless one
< ? Luck of the starving camel?