List of stars in Hydrus
|Pronunciation||//, genitive //|
|Symbolism||the water snake|
|Right ascension||0.08 h ~ 4.66 h|
|Declination||−58° ~ −82°|
|Area||243 sq. deg. (61st)|
|Stars with planets||4|
|Stars brighter than 3.00m||2|
|Stars within 10.00 pc (32.62 ly)||1|
|Brightest star||β Hyi (2.82m)|
|Nearest star||β Hyi
(24.38 ly, 7.47 pc)
Hydrus (pron.: //) is a small constellation in the southern sky, created in the sixteenth century. Its name means "male water snake", and it should not be confused with Hydra, a much larger constellation which represents a female water snake.
Hydrus was one of twelve constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman and it first appeared on a 35-cm diameter celestial globe published in 1597 (or 1598) in Amsterdam by Plancius with Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. The companion to Hydra, the female water snake, he is forced to journey through Eridanus, Orion, and the Milky Way to visit his lover.
Notable features 
Hydrus does not contain any particularly bright stars. Beta Hydri, the brightest star in Hydrus, is a yellow star of magnitude 2.8, 24 light-years from Earth. Alpha Hydri is a white main-sequence star of magnitude 2.9, 71 light-years from Earth. Gamma Hydri is a red giant of magnitude 3.2, 214 light-years from Earth.
There is one notable double star in Hydrus. Pi Hydri, composed of Pi1 Hydri and Pi2 Hydri, is divisible in binoculars. Pi1 is a red star of magnitude 5.6, 740 light-years from Earth. Pi2 is an orange star of magnitude 5.7, 468 light-years from Earth.
Deep-sky objects 
The constellation contains IC 1717.
Extrasolar planets 
In August 2010, a European astronomical team working at the La Silla Observatory in Chile announced that they had confirmed the presence of at least five planets orbiting the star HD 10180 in Hydrus.
See also 
- Ridpath, Ian; Tirion, Wil (2001), Stars and Planets Guide, Princeton University Press, ISBN 0-691-08913-2
- Ridpath, Ian; Tirion, Wil (2007), Stars and Planets Guide, Princeton University Press, ISBN 978-0-691-13556-4
- Staal, Julius D.W. (1988), The New Patterns in the Sky, McDonald and Woodward Publishing Company, ISBN 0-939923-04-1
|Wikimedia Commons has media related to: Hydrus|
- Chandra information about Hydrus
- The Deep Photographic Guide to the Constellations: Hydrus
- Star Tales – Hydrus