4_Aquarii
4 Aquarii
Star in the constellation Aquarius
4 Aquarii (abbreviated 4 Aqr) is a binary star system in the constellation Aquarius,[9] located approximately 198 light years away from the Sun.[1] 4 Aquarii is the Flamsteed designation. It is visible to the naked eye as a dim, yellow-white hued star with a combined apparent visual magnitude of 5.99.[2] The system is moving closer to the Earth with a heliocentric radial velocity of −21.5 km/s.[5]
This is a visual binary with an orbital period of 200.7 years and an eccentricity of 0.535.[7] The magnitude 6.40[3] primary, designated component A, is an F-type subgiant star with a stellar classification of F7 IV,[4] suggesting that it has exhausted the hydrogen at its core and evolved off the main sequence.[7] It has a dynamically-measured mass 1.6[7] times that of the Sun and is radiating 11 times the Sun's luminosity from its photosphere at an effective temperature of 6,440 K.[6] The magnitude 7.43[3] secondary, component B, is a suspected F-type main-sequence star of class F6 V.[4] The pair are an estimated 1.6 billion years old.[8]