In our solar system, there are several thousand examples of co-orbital objects: bodies that share the same orbit around the sun or a planet. The Trojan asteroids are such an example. We have not yet observed any similar co-orbitals in extrasolar systems, despite discovering more than 5,000 exoplanets. In a new study published in Icarus by Anthony Dobrovolskis, SETI Institute, and Jack Lissauer, NASA Ames Research Center, the authors theorize that some Trojan exoplanets form, but the ones that are large and on short-period orbits (and thus relatively easy to detect) are typically forced out of shared orbit by tides. They collide with either their star or their giant planet when that happens.
Click here for original story, Why haven’t we discovered co-orbital exoplanets? Tides may offer a possible answer
Source: Phys.org