Gamma Herculis

Gamma Herculis is a white fourth-magnitude star in the southeastern regions of Hercules, some three degrees southward of Kornephoros or Beta Herculis. 'Gamma' is the third letter of the Greek alphabet and so, in principle, this should be the third brightest star in its constellation. The Bayer desginations of Hercules are arranged somewhat arbitrarily, however, and Gamma Herculis is actually the constellation's ninth brightest star (the actual third brightest star in Hercules is Delta Herculis, also called Sarin). It lies some 193 light years from the Sun, in the direction of a wide field of galaxies known as the Hercules Galaxy Cluster.

Gamma Herculis is a hot giant star in the later stages of its life cycle. Having expanded to more the four times the Sun's diameter, it emits approximately a hundred times as much light. Variations in its spectrum reveal that it has a companion star, and thus forms a binary system, though this companion is only detectable through spectroscopic means. There are indications that Gamma Herculis is a semiregular variable, showing minor and unpredictable fluctuations in its brightness over time.