TW Piscis Austrini

TW Piscis Austrini (also Fomalhaut B) is a dwarf star in the constellation Piscis Austrinus. It lies relatively close to the Sun, at an estimated distance of 24.8 light years.
To an observer on Earth the star is visually separated from its larger companion Fomalhaut A by 2 degrees - the width of four full moons.
The TW in the name is a variable star designation. This is a variable star of the type known as a BY Draconis variable, with surface brightness variations causing the changes as the star rotates. It varies slightly in apparent magnitude, ranging from 6.44 to 6.51 over a 10.3 day period.
TW Piscis Austrini lies within a light year of Fomalhaut A. Due to sharing the same proper motion, and the same estimated age of approximately 440±40 million years, astronomers now consider them to be elements of a multiple star system. A third star, dimmer, and more widely separated, Fomalhaut C, gives the system the widest visual separation, to observers from Earth, at approximately 6 degrees. 
In 2019, an exoplanet candidate around Fomalhaut B was detected by astrometry.