Hydrus IAU
List of stars in Hydrus
Abbreviation Hyi
Genitive Hydri
Pronunciation /ˈhdrəs/, genitive /ˈhdr/
Symbolism the water snake
Right ascension 0.08 h ~ 4.66 h
Declination −58° ~ −82°
Quadrant SQ1
Area 243 sq. deg. (61st)
Main stars 3
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)
Messier objects none
Meteor showers none
Phoenix (corner)
Visible at latitudes between +8° and −90°.
Best visible at 21:00 (9 p.m.) during the month of November.

Hydrus (play /ˈhdrəs/) 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[1] 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.[2][3] The companion to Hydra, the female water snake, he is forced to journey through Eridanus, Orion, and the Milky Way to visit his lover.[3]

Notable features


Hydra 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.[1]

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.[1]

The only star in Hydrus that anyone seems to have named is γ Hyi, which in China is known as Foo Pih.

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.[4]

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 

External links

Template:Stars of Hydrus

Coordinates: Celestia 02h 00m 00s, −70° 00′ 00″

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