Hydrus

Hydrus
Constellation
Hydrus
AbbreviationHyi
GenitiveHydri
Pronunciation/ˈhdrəs/, genitive /ˈhdr/
Symbolismthe water snake
Right ascension00h 06.1m to 04h 35.1m [1]
Declination−57.85° to −82.06°[1]
QuadrantSQ1
Area243 sq. deg. (61st)
Main stars3
Bayer/Flamsteed
stars
19
Stars with planets4
Stars brighter than 3.00m2
Stars within 10.00 pc (32.62 ly)1
Brightest starβ Hyi (2.82m)
Messier objectsnone
Meteor showersnone
Bordering
constellations
Dorado
Eridanus
Horologium
Mensa
Octans
Phoenix (corner)
Reticulum
Tucana
Visible at latitudes between +8° and −90°.
Best visible at 21:00 (9 p.m.) during the month of November.

Hydrus /ˈhdrəs/ is a small constellation in the deep southern sky. It 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 (14 in) diameter celestial globe published in late 1597 (or early 1598) in Amsterdam by Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. The French explorer and astronomer Nicolas Louis de Lacaille charted the brighter stars and gave their Bayer designations in 1756. Its name means "male water snake", as opposed to Hydra, a much larger constellation that represents a female water snake. It remains below the horizon for most Northern Hemisphere observers.

The brightest star is the 2.8-magnitude Beta Hydri, also the closest reasonably bright star to the south celestial pole. Pulsating between magnitude 3.26 and 3.33, Gamma Hydri is a variable red giant 60 times the diameter of the Sun. Lying near it is VW Hydri, one of the brightest dwarf novae in the heavens. Four star systems in Hydrus have been found to have exoplanets to date, including HD 10180, which could bear up to nine planetary companions.

  1. ^ a b Cite error: The named reference boundary was invoked but never defined (see the help page).