Hydrus

Hydrus /ˈhaɪdrəs/ is a small constellation in the deep southern sky. It was first depicted on a celestial atlas by Johann Bayer in his 1603 Uranometria. 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 some 60 times the diameter of our Sun. Lying near it is VW Hydri, one of the brightest dwarf novae in the heavens. Four star systems have been found to have exoplanets to date, most notably HD 10180, which could bear up to nine planetary companions. ... Characteristics. Irregular in shape, Hydrus is bordered by Mensa to the southeast, Eridanus to the east, Horologium and Reticulum to the northeast, Phoenix to the north, Tucana to the northwest and west, and Octans to the south; Lacaille had shortened Hydrus' tail to make space for this last constellation he had drawn up. ... Stars. ... Beta Hydri, the brightest star in Hydrus, is a yellow star of apparent magnitude 2.8, lying 24 light-years from Earth. ... It is also the closest bright star to the south celestial pole. ... Located at the northern edge of the constellation and just southwest of Achernar is Alpha Hydri, a white sub-giant star of magnitude 2.9, situated 72 light-years from Earth. ... A line drawn between Alpha Hydri and Beta Centauri is bisected by the south celestial pole. ... In the southeastern corner of the constellation is Gamma Hydri, a red giant of spectral type M2III located 214 light-years from Earth. It is a semi-regular variable star, pulsating between magnitudes 3.26 and 3.33. ... Deep-sky objects. ... Known as the white rose galaxy, PGC 6240 is a giant spiral galaxy surrounded by shells resembling rose petals, located around 345 million light years from our Solar System. Unusually, it has cohorts of globular clusters of three distinct ages suggesting bouts of post-starburst formation following a merger with another galaxy. The constellation also contains a spiral galaxy NGC 1511 that lies edge on to observers on Earth and is readily viewed in amateur telescopes. Located mostly in Dorado, the Large Magellanic Cloud extends into Hydrus. The globular cluster NGC 1466 is an outlying component of the galaxy, and contains many RR Lyrae-type variable stars. ... NGC 602 is composed of an emission nebula and a young, bright open cluster of stars that is an outlying component on the eastern edge of the Small Magellanic Cloud, a satellite galaxy to the Milky Way. [Hydrus. Wikipedia]