Magnitude 4.71 Apparent magnitude (V) 4.71 | Constellation Aquarius | |
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People also search for Mu Aquarii, Rho Aquarii, Iota Aquarii | ||
Omicron Aquarii (ο Aqr, ο Aquarii) is the Bayer designation for a star in the equatorial constellation of Aquarius. It has the traditional star name Kae Uh, from the Chinese 蓋屋 (Mandarin gàiwū) "the roof". Visible to the naked eye, it has an apparent visual magnitude of +4.71. Parallax measurements put it at a distance of roughly 440 light-years (130 parsecs) from Earth.
In Chinese, 蓋屋 (Gài Wū), meaning Roofing, refers to an asterism consisting of ο Aquarii and 32 Aquarii. Consequently, ο Aquarii itself is known as 蓋屋一 (Gài Wū yī, English: the First Star of Roofing.)
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 70° ± 20°. 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.