A 4-star system caught eclipsing itself in a way never seen before

Astronomers have discovered a never-before-seen four-star system, TIC 433545934, that demonstrates unique behavior. This system consists of two pairs of stars orbiting each other, forming a 2+2 type quadruple star system. Each pair, designated as A and B, is an eclipsing binary, meaning the two stars within each pair periodically pass in front of each other, causing a regular dip in brightness when observed from Earth.

When both pairs are observed simultaneously, their light blends together, creating a more complex pattern. However, confirming the system's gravitational binding has proven challenging, as astronomers cannot immediately determine if the pairs are gravitationally bound or simply aligned by chance.

The key to confirming this system's structure lies in eclipse timing variations, where synchronized wobbles in both binaries' eclipses indicate gravitational binding. In this case, astronomers led by Tamás Borkovits of the Baja Astronomical Observatory in Hungary observed a rare event in TIC 433545934—a triple-dip eclipse, where the two entire binary pairs pass in front of each other, a phenomenon never before confirmed in a 2+2 quadruple star system.

One pair of stars, A, consists of two closely matched, slightly aged stars, while the other pair, B, features one dominant star and one much lighter companion. Together, the inner pairs orbit each other every 224.5 days. Despite their internal differences, the entire four-star system is remarkably flat, with all orbits aligned within 2 degrees of one another.