From Wikipedia, the free encyclopedia

Serpens

Click for larger image
List of stars in Serpens
Abbreviation:	Ser
Genitive:	Serpentis
Symbology:	the Snake
Right ascension:	Serpens Caput: 16 h Serpens Cauda: 18 h
Declination:	Serpens Caput: +10° Serpens Cauda: −5°
Area:	637 sq. deg. (23rd)
Main stars:	9
Bayer/Flamsteed stars:	60
Stars known to have planets:	4
Bright stars:	1
Nearby stars:	3
Brightest star:	α Ser (Unukalhai) (2.63m)
Nearest star:	γ Ser (36.3 ly)
Messier objects:	2
Meteor showers:
Bordering constellations:	Serpens Caput: Corona Borealis Boötes Virgo Libra Ophiuchus Hercules Serpens Cauda: Aquila Ophiuchus Sagittarius Scutum
Visible at latitudes between +80° and −80° Best visible at 21:00 (9 p.m.) during the month of July

Serpens (pronounced /ˈsɝpənz/, Latin for "snake") is one of the 88 modern constellations, and was also one of the 48 listed by Ptolemy. Among the modern constellations it is unique in being split into two pieces, Serpens Caput (representing the head of the snake) to the west and Serpens Cauda (representing the tail) to the east. Between these two pieces lies the constellation of Ophiuchus, the serpent holder.

Since Serpens is regarded as one constellation despite being split into two halves, the ordering of Bayer designations goes in order of brightness among both halves.

Only one of the stars in Serpens is brighter than third magnitude, so the constellation is not easy to perceive. α Serpentis, named Unukalhai, is in the head part. δ Serpentis, also in the head, is a double star 210 light-years from Earth. θ Serpentis, in the tail, is also double.

Stars in the head include α, β, γ, δ, ε, ι, κ, λ, μ, π, ρ, σ, τ, χ and ω Serpentis. Stars in the tail include ζ, η, θ, ν, ξ, and ο Serpentis.

Messier 5, a globular cluster located approximately 8° southwest of α Serpentis in the head.

Messier 16 is a young open cluster associated with the Eagle Nebula, a diffuse nebula which is a region of current star formation in the tail.

MWC 922, a nebula in the Mount Wilson Catalog, is a Symmetric Bipolar Nebula notable for its appearance as a perfectly symmetrical square or rectangle. It is also known as IRAS 18184-1302, and located at RA: 18:21:16 DEC: -13:01:27, near M16 in Serpens Cauda. The MWC is from Mount Wilson Observatory.

Part of the Milky Way passes through the tail, as illustrated by the shaded regions of the star map.

The Serpens South star cluster was uncovered by NASA's Spitzer Space Telescope in the southern portion of the Serpens cloud. The discovery was possible due to the infrared observation capabilities of the SST because at visible wavelengths the stars are completely obscured by interstellar dust in the Serpens cloud.

Serpens is the snake being grasped by Ophiuchus, the Snake-Handler, and is thus very closely associated with it. Both were listed as constellations by Ptolemy. Originally, Serpens and Ophiuchus were considered a single Snake-Holder constellation, out of which developed an associated myth of the founding of medicine.

• Ian Ridpath and Wil Tirion (2007). Collins Stars and Planets Guide, HarperCollins, London. ISBN 978-0007251209.

Wikimedia Commons has media related to:

Serpens

• The Deep Photographic Guide to the Constellations: Serpens
• Star Tales – Serpens
• Stellar Siblings in Serpens South