Sagitta

Sagitta

Constellation
List of stars in Sagitta
Abbreviation	Sge
Genitive	Sagittae
Pronunciation	/səˈdʒɪtə/ Sagítta, genitive /səˈdʒɪtiː/
Symbolism	the Arrow
Right ascension	19.8333
Declination	+18.66
Area	80 sq. deg. (86th)
Main stars	4
Bayer/Flamsteed stars	19
Stars with known planets	1
Bright stars	0
Nearby stars	0
Brightest star	γ Sge (3.47m)
Nearest star	15 Sge (57.7 ly)
Messier objects	1
Bordering constellations	Vulpecula Hercules Aquila Delphinus
Visible at latitudes between +90° and −70°. Best visible at 21:00 (9 p.m.) during the month of August.

Sagitta is a constellation. Its name is Latin for arrow, and it should not be confused with the larger constellation Sagittarius, the archer. Although ancient, it is insignificant, for it has no star brighter than the 4th magnitude and is the third smallest of all constellations (only Equuleus and Crux are smaller). It was included among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations defined by the International Astronomical Union. Located not very far to the north of the equator, this constellation can be seen from everywhere on Earth except for within the Antarctic circle.

Sagitta lies within the Milky Way and is bordered by the following constellations (beginning at the north and then continuing clockwise): the little fox Vulpecula, the mythological hero Hercules, the Eagle Aquila and the Dolphin Delphinus.

Notable features

Stars

Here are some of Sagitta's brightest stars

• α Sge: also known as Sham, this yellow bright giant star of spectral class G1 II (with 4.37m) lies at a distance of 610 light-years and together with β Sge (also 4.37m) forms either the feathers of the shaft or the two-pointed arrow once used in the Roman army.
• γ Sge: this cool giant (M0 III, 3.47m) represents with the stars δ Sge and ε Sge the shaft. It lies at a distance of merely 170 light-years.
• δ Sge: M2 II+A0 V (suspected visual double; probably single image, composite spectrum), 3.82m
• ε Sge: G8 III, 5.66m, multiple star (4 components; component B is optical)
• η Sge: this star of spectral class K2 III with 5.1m belongs to the Hyades moving group.

Deep sky objects

• M71: this object is a very loose globular cluster mistaken for quite some time for a dense open cluster. It lies at a distance of about 13,000 light-years from Earth and was first discovered by the French astronomer Philippe Loys de Chéseaux in the year 1745 or 1746.

History

The Greeks who are sometimes believed^[1] to have formed this constellation called it Oistos^[2]. The Romans named it Sagitta.^{[citation needed]}

This constellation is one of those cases where Johann Bayer choosed to name the stars in a non-brightness order, in this case even putting the brightest star to a mere γ. Another example of such a deviation from the usual brightness order is the constellation Sagittarius.

Mythology

Although Sagitta doesn't contain any bright stars, its shape is reminiscent of an arrow, and many cultures have interpreted it thus, among them the Persians^{[citation needed]}, Hebrews^{[citation needed]}, Greeks and Romans. The Arabs called it as-Sahm, a name that was transferred and confused to the name Sham now referring to α Sge only.

Ancient Greece

In Ancient Greece, Sagitta was regarded as the weapon that Hercules used to kill the eagle (Aquila) of Jove that perpetually gnawed Prometheus' liver.^[3] The Arrow is located beyond the north border of Aquila, the Eagle. Others believe the Arrow to be the one shot by Hercules towards the adjacent Stymphalian birds (6th labor) who had claws, beaks and wings of iron, and who lived on human flesh in the marshes of Arcadia - Aquila the Eagle and Cygnus the Swan, and Lyra the Vulture - and still lying between them, whence the title Herculea. Eratosthenes claimed it as the arrow with which Apollo exterminated the Cyclopes.^[3]

See also

• Sagittarius

References

• Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0007251209. Princeton University Press, Princeton. ISBN 978-0691135564.

External links

• The Deep Photographic Guide to the Constellations: Sagitta
• Star Tales – Sagitta

Wikimedia Commons has media related to: Sagitta

Coordinates: 19^h 50^m 00^s, +18° 40′ 00″