Lambda Aquarii

Lambda Aquarii (λ Aqr, λ Aquarii), informally known as Hydor /ˈhaɪdɔːr/, is the Bayer designation for a star in the equatorial constellationof Aquarius. The apparent visual magnitude of this star is 3.722, which is bright enough to be visible with the naked eye. It is roughly 390 light-years (120 pc) from Earth.

Lambda Aquarii is a red giant star with a stellar classification of M2.5 III. It is classified as slow irregular variable and pulsation periods of 24.5, 32.0, and 49.5 days have been identified. This star is on the asymptotic giant branch and is generating energy through the nuclear fusion of hydrogen and helium along concentric shells surrounding an inert core of carbon and oxygen.