The French explorer and astronomer Nicolas Louis de Lacaille charted the brighter stars and gave their Bayer designations in 1756.
The French explorer and astronomer Nicolas Louis de Lacaille called it l’Hydre Mâle on the 1756 version of his planisphere of the southern skies, distinguishing it from the feminine Hydra.
Lacaille charted and designated 20 stars with the Bayer designations Alpha through to Tau in 1756.
The French name was retained by Jean Fortin in 1776 for his Atlas Céleste, while Lacaille Latinised the name to Hydrus for his revised Coelum Australe Stelliferum in 1763. ==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.
The French name was retained by Jean Fortin in 1776 for his Atlas Céleste, while Lacaille Latinised the name to Hydrus for his revised Coelum Australe Stelliferum in 1763. ==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.
The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Hyi".
The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 12 segments.
The system is a complex one as the faint star GJ 3021B orbits at a distance of 68 AU; it is a red dwarf of spectral type M4V. HD 20003 is a star of magnitude 8.37.
A planet, Eta2 Hydri b, greater than 6.5 times the mass of Jupiter was discovered in 2005, orbiting around Eta2 every 711 days at a distance of 1.93 astronomical units (AU). Three other systems have been found to have planets, most notably the Sun-like star HD 10180, which has seven planets, plus possibly an additional two for a total of nine—as of 2012 more than any other system to date, including the Solar System.
A planet, Eta2 Hydri b, greater than 6.5 times the mass of Jupiter was discovered in 2005, orbiting around Eta2 every 711 days at a distance of 1.93 astronomical units (AU). Three other systems have been found to have planets, most notably the Sun-like star HD 10180, which has seven planets, plus possibly an additional two for a total of nine—as of 2012 more than any other system to date, including the Solar System.
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Page generated on 2021-08-05