Star system
A recently discovered quintuple star system (five stars) is known as 1SWASP J093010.78+533859.5. The system has two sets of binary stars, one of them with a small third star. The two sets are a long way apart, further than the orbit of Pluto is to the Sun. The binary stars are close to each other and one binary has touching stars, with their outer ionised gases mixing. That situation is called a contact binary. From the data collected, the authors are fairly sure that both binaries (and probably all five stars) are gravitationally bound in a single system. The angles of inclination (the angle between the two orbital planes) of the two binaries (88.2(3) and 86(4) degrees). This suggests they originally formed by break-up (~9-10 billion years ago ago) from a single protostellar disk. Afterwards, they stayed in the same orbital plane.