Phi Aquarii

Phi Aquarii is a binary star system in the equatorial constellation of Aquarius. Its name is a Bayer designation that is Latinized from φ Aquarii, and abbreviated Phi Aqr or φ Aqr. This system is visible to the naked eye as a point of light with a combined apparent visual magnitude of +4.223. Parallax measurements indicate its distance from Earth is approximately. It is drifting further away with a radial velocity of +2.5 km/s. The system is positioned 1.05 degrees south of the ecliptic so it is subject to lunar occultations.
This is a spectroscopic binary star system with an estimated period of. The primary component is an aging red giant star with a stellar classification of M1.5 III. At an estimated age of 11 billion years, it has exhausted the supply of hydrogen at its core and evolved away from the main sequence. The star has the same mass as the Sun, but has expanded to 35 times the Sun's girth. It is radiating 208 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 3,715 K, giving it the reddish hue of an M-type star.
On 6 September 2019, it had a close conjunction with Neptune.