Alpha Hydri

Based upon parallax measurements from the Hipparcos mission, Alpha Hydri is located at a distance of about 71.8 light-years (22.0 parsecs) from Earth. This subgiant star is 3.3 times larger and 2.1 as massive as the Sun, with a stellar classification of F0 IV. It is about 810 million years old and is radiating 21 times the Sun's luminosity from its outer atmosphere at an effective temperature of 7,059 K. Alpha Hydri emits X-rays similar to Altair. The space velocity components of this star are [U, V, W] = [−14, −14, -2] km/s.

Naming

In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, 蛇首 (Shé Shǒu), meaning Snake's Head, refers to an asterism consisting of α Hydri and β Reticuli. Consequently, α Hydri itself is known as 蛇首一 (Shé Shǒu yī, English: the First Star of Snake's Head.)