An Etymological Dictionary of Astronomy and Astrophysics

The brightest star as well as the Alpha star of → Serpens, thus also known as α Serpentis. It is a third magnitude (V = 2.65) an orange giant of spectral type K2 with a radius 15 times as large as that of the Sun and a surface temperature of 4300 kelvins. It is approximately 73.2 light years from Earth.
Unukalhai is in fact a triple star system. The second star (α Serpentis B) is 58 arcseconds from the primary and has a magnitude of 11.8. The third star (α Serpentis C), 13th magnitude, lies 2.3 arcminutes from A. Other designations: Cor Serpentis, HR 5854, HD 140573.

See also: From Ar. ‘unuq al-hayyah (عنق‌الحیه) “Neck of the Snake,” from ‘unuq “neck” + al-hayyah “snake.”