Alshain

Beta Aquilae (β Aquilae, abbreviated Beta Aql, β Aql) is a binary star in the equatorial constellation of Aquila. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 44.7 light-years from the Sun. Its two components are designated Beta Aquilae A (formally named Alshain /ælˈʃeɪn/, the traditional name for the system) and B.

The primary (Beta Aquilae A) is of magnitude 3.71 and spectral class G8IV. It has a very low level of surface magnetic activity and may be in a state similar to a Maunder minimum. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. A subgiant with a mass 30% greater than the Sun's, a luminosity six times that of the Sun, and a radius about thrice solar.

The secondary (Beta Aquilae B) is a 12th magnitude companion which is 13 arcseconds away in the sky. It is a class M red dwarf with a mass a third that of the Sun and a luminosity 2.5% the Sun's.