3 Piscis Austrini
3 Piscis Austrini, also known as HD 201901, is a suspected astrometric binary star system that, despite its Flamsteed designation, is actually located in the constellation Microscopium. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 5.41. The system is moving closer to the Earth with a heliocentric radial velocity of −46 km/s. It is following a highly elliptical orbit around the Galactic Center, moving between a pericenter of out to an apocenter of, with an orbital eccentricity of 0.49.
The visible component is an evolved giant star with a stellar classification of K3 III. The interferometry-measured angular diameter of the star, after correcting for limb darkening, is, which, at its estimated distance, equates to a physical radius of about 20 times the radius of the Sun. It is radiating 174 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,050 K.
