Astronomers have seen the star, named HR 5171, before. In a new study, however, an international team of scientists learned much more about it. For example, they discovered that HR 5171 is a binary system with a small companion star that touches and orbits the larger star. The astronomers also calculated HR 5171 A's (the bigger star's) surprising size. The star is almost twice as large as scientists expect for stars of its type.