Grus (constellation)

Grus

Constellation
List of stars in Grus
Abbreviation	Grus
Genitive	Gruis
Pronunciation	/ˈɡrʌs/, or colloquially /ˈɡruːs/; genitive /ˈɡruːɨs/
Symbolism	the Crane
Right ascension	22 h
Declination	−47°
Quadrant	SQ4
Area	366 sq. deg. (45th)
Main stars	7
Bayer/Flamsteed stars	28
Stars with planets	5
Stars brighter than 3.00m	3
Stars within 10.00 pc (32.62 ly)	1
Brightest star	α Gru (Alnair) (1.73m)
Nearest star	Gliese 832 (16.11 ly, 4.94 pc)
Messier objects	0
Meteor showers	????? ?????
Bordering constellations	Piscis Austrinus Microscopium Indus Tucana Phoenix Sculptor
Visible at latitudes between +34° and −90°. Best visible at 21:00 (9 p.m.) during the month of October.

Grus (pron.: /ˈɡrʌs/, or colloquially /ˈɡruːs/) is a constellation in the southern sky. Its name is Latin for the crane, a species of bird. It was introduced in the late 16th century.

History

The stars that form Grus were originally considered part of Piscis Austrinus (the southern fish). The Arabic name of Gamma Gruis (al-dhanab, "the tail") reflects this origins.

The stars were first defined as a separate constellation by Petrus Plancius, who created twelve new constellations based on the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Grus first appeared on a 35-cm diameter celestial globe published in 1597 (or 1598) in Amsterdam by Plancius with Jodocus Hondius. Its first depiction in a celestial atlas was in Johann Bayer's Uranometria of 1603.

An alternative name for the constellation, Phoenicopterus (Latin for flamingo), was used briefly during the early 17th century.

Grus represents a crane, though it is sometimes seen as a flamingo. There are no ancient myths associated with Grus.

Notable features

The constellation Grus as it can be seen by the naked eye.

Stars

See also: List of stars in Grus

Grus has several bright stars. Alpha Gruis, called Alnair, is a blue-white star of magnitude 1.7, 101 light-years from Earth. Its traditional name, Alnair, means "the bright one" and refers to its status as the brightest star in Grus. Beta Gruis is a red giant variable star with a minimum magnitude of 2.3 and a maximum magnitude of 2.0; it is 170 light-years from Earth. Gamma Gruis is a blue giant of magnitude 3.0, 203 light-years from Earth.

There are several celebrated naked-eye double stars in Grus. Delta Gruis, composed of Delta¹ Gruis and Delta² Gruis, is an optical double. Delta¹ is a yellow giant of magnitude 4.0, 296 light-years from Earth, and Delta² is a red giant of magnitude 4.1, 325 light-years from Earth. Mu Gruis, composed of Mu¹ Gruis and Mu² Gruis, is also an optical double. Mu¹ is the brighter of the two at magnitude 4.8 - it is 262 light-years from Earth - and Mu² the dimmer at magnitude 5.is 240 light-years from Earth. Pi Gruis, an optical double with a variable component, is composed of Pi¹ Gruis and Pi². Pi¹ is a semi-regular red giant with a minimum magnitude of 6.7 and a maximum magnitude of 5.4. It has a period of 150 days and is 500 light-years from Earth. Pi² is a white giant 132 light-years from Earth and is often brighter than its companion at magnitude 5.6.

Equivalents

The stars that correspond to Grus cannot all be seen from China. In Chinese astronomy some of them are located in the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ), while the rest were placed among the Southern Asterisms (近南極星區, Jìnnánjíxīngōu) by Xu Guangqi, based on knowledge of western star charts.

See also

• List of the star names in Grus
• Grus (Chinese astronomy)
• List of brightest stars

References

• Ridpath, Ian; Tirion, Wil (2001), Stars and Planets Guide, Princeton University Press, ISBN 0-691-08913-2 
• Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0-00-725120-9. Princeton University Press, Princeton. ISBN 978-0-691-13556-4.

External links

• The Deep Photographic Guide to the Constellations: Grus
• The clickable Grus
• Starry Night Photography - Grus Constellation
• Star Tales – Grus
• StellaNavigator: Grus Constellation
• October Constellations