Nu Aquarii

Lore & Background

Nu Aquarii has exhausted the hydrogen at its core and evolved into a giant star with a stellar classification of G8 III. It has double the mass of the Sun and has expanded to eight times the Sun's radius, radiating 37 times the Sun's luminosity. The star is drifting closer to the Sun with a radial velocity of −11 km/s.

Together with μ Aquarii, it forms the name Albulaan, derived from the Arabic term al-bulaʽān, meaning 'the two swallowers'. This star, along with ε Aqr (Albali) and μ Aqr (Albulaan), were part of al Bulaʽ—the Swallower. In Chinese astronomy, Nu Aquarii belongs to an asterism called Celestial Ramparts, which includes several other stars in Aquarius and Capricornus.

Reader's Guide

Nu Aquarii holds significance as a component of the traditional Arabic asterism al Bulaʽ, the Swallower, alongside ε Aquarii and μ Aquarii. Its pairing with μ Aquarii as Albulaan reflects a cultural naming tradition that has been preserved in modern star nomenclature. The star's evolution into a G-type giant provides a tangible example of stellar aging, having exhausted its core hydrogen after an estimated 708 million years. Its yellowish hue, characteristic of G-type stars, and its measurable drift toward the solar system contribute to its value in studies of stellar kinematics and galactic motion. In Chinese astronomy, its inclusion in the Celestial Ramparts asterism demonstrates how different cultures have grouped stars into meaningful patterns. Though faintly visible to the naked eye, Nu Aquarii's physical properties—mass, radius, and luminosity—offer a clear contrast to the Sun, illustrating the later stages of stellar evolution for stars of similar initial mass.