Omicron Aquarii
Omicron Aquarii, Latinized from ο Aquarii, is the Bayer designation for a star in the equatorial constellation of Aquarius. Visible to the naked eye, it has an apparent visual magnitude of +4.71. Parallax measurements put it at a distance of roughly from Earth.
It has the traditional star name Kae Uh, from the Chinese 蓋屋.
In Chinese astronomy, 蓋屋 is the rooftop, an asterism consisting of ο Aquarii and 32 Aquarii. Consequently, the Chinese name for ο Aquarii itself is 蓋屋一
The spectrum of Omicron Aquarii fits a stellar classification of B7 IVe; the luminosity class of IV suggests that this is a subgiant star that is exhausting the supply of hydrogen at its core and is in the process of evolving into a giant star. The 'e' suffix on the class indicates that the spectrum shows emission lines of hydrogen, thus categorizing this as a Be star. Omicron Aquarii is rotating rapidly with a projected rotational velocity of 205 km/s. The rotation rate along the equator may be as high as 77% of the critical rotation velocity, with the axis of rotation being inclined by around. The emission lines are being generated by a decreted circumstellar disk of hot hydrogen gas.
It is classified as a Gamma Cassiopeiae type variable star and its brightness varies from magnitude +4.68 to +4.89.
