Eta Gruis

Eta Gruis, Latinized from η Gruis, is a solitary star in the southern constellation of Grus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.85. Based upon an annual parallax shift of $27.8$ as seen from the Earth, the system is located about 460 light years from the Sun. The star is drifting further away with a radial velocity of +28 km/s.

This object is an evolved K-type giant star with a stellar classification of K2 III CNIV, where the suffix notation indicates this is an intermediate CN star. It is a periodic microvariable with an amplitude of 0.0055 magnitude and a frequency of 0.36118 cycles per day. With the supply of hydrogen exhausted at its core, the star has expanded and cooled, now having 31 times the Sun's girth. It is radiating 338.5 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,420 K.

Eta Gruis has a magnitude 11.5 visual companion located at an angular separation of $31.38$ along a position angle of 187°, as of 2012.