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Gamma Herculis
Gamma Herculis (γ Herculis, γ Her) is a magnitude 3.74 binary star system in the northern constellation of Hercules.〔
==Properties==
This is known to be a spectroscopic binary system,〔 although there is no information about the secondary component.〔 Based upon parallax measurements, this system is located at a distance of about from the Earth.〔 The spectrum of the primary star matches a stellar classification of A9III, which indicates this is a giant star that has exhausted the hydrogen at its core and evolved away from the main sequence. The effective temperature is about 7,031 K,〔 giving the star a white hue characteristic of A-type stars.〔 It is rotating rapidly with a projected rotational velocity of .〔 The interferometry-measured angular diameter of this star is ,〔 which, at its estimated distance, equates to a physical radius of about six times the radius of the Sun.〔
Observations by German astronomer Ernst Zinner in 1929 gave indications that this may be a variable star. It was listed in the ''New Catalogue of Suspected Variable Stars'' (1981) with a magnitude range of 3.74 to 3.81. Further observations up to 1991 showed a pattern of small, slow variations with a magnitude variation of 0.05. These appeared to repeat semi-regularly with a period of 183.6 days, although the spectroscopic data presented a longer period of 165.9 days.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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