Delta Hydrae

Delta Hydrae, Latinized from δ Hydrae, is a double star in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 4.146. Based upon an annual parallax shift of 20.34 mas, it is located about 160 light years from the Sun.
This is a double star with an angular separation of along a position angle of , as of 2003. The brighter component is an A-type main sequence star with a stellar classification of A1 Vnn. It is spinning rapidly with a projected rotational velocity of 285 km/s. This is giving the star an oblate shape with an equatorial bulge that is 20% larger than the polar radius. It has an estimated 2.88 times the mass of the Sun and 2.7 times the Sun's radius. The star is about 244 million years old and it radiates 42.7 times the solar luminosity from its outer atmosphere at an effective temperature of 11,055 K.
The companion has a visual magnitude of 11.15. X-ray emissions have been detected from this location in space, which may be coming from a companion star.
Name and etymology.
In the catalogue of stars in the "Calendarium of Al Achsasi Al Mouakket", this star was designated "Lisan al Shudja", which was translated into Latin as "Lingua Hydri", meaning "the snake's tongue". This star, along with ε Hya, ζ Hya, η Hya, ρ Hya and σ Hya (Minchir), were Ulugh Beg's "Min al Azʽal", "Belonging to the Uninhabited Spot".
According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "Min al Azʽal" or "Minazal" were the title for five stars :δ Hya as "Minazal I", η Hya as "Minazal II", ε Hya as "Minazal III", ρ Hya as "Minazal IV" and ζ Hya as "Minazal V" (exclude σ Hya)
In Chinese, (), meaning "Willow (asterism)", refers to an asterism consisting of δ Hydrae, σ Hydrae, η Hydrae, ρ Hydrae, ε Hydrae, ζ Hydrae, ω Hydrae and θ Hydrae Consequently, δ Hydrae itself is known as (, .)
The people of Groote Eylandt called "Unwala", "The Crab", for the star cluster including this star, ε Hya, ζ Hya, η Hya, ρ Hya and σ Hya (Minchir).