The authors of the new work modeled the behavior of planets around binary stars and came to the conclusion that under such conditions it is much easier for objects to leave their systems .
In lightless interstellar space, many orphan planets can fly away, being “separated” from their normal orbits by gravity or by strong collisions with other objects in their system. At the same time, the conditions to “free” the planet from the gravitational pull of the star and other planets are quite strict: the system must be “compact”. And according to some estimates, there are more “orphan” planets than “normal” planets. This means that the mechanism for releasing them will be much simpler and the conditions less stringent.
The authors of the new work, using computer modeling, have shown that the origin of the orphan planets could be “spiral” binaries – systems with two stars with inclined orbital planes compared to each other. In single-star systems, the planets must be in close orbit for a planet to escape. According to new research, in two-star systems, planets can be quite far apart – and still leave. Indeed, the gravitational interaction between the two stars and other planets in such systems is more than enough to destabilize the orbits of some planets. In this case, the largest planet plays an important role and does not change its position. In binary stars orbiting in circular orbits, the gravitational influence of a Neptune-sized object is enough to form orphan stars. In systems with elliptical orbits, a super-Earth has 10 times the mass of our planet. Note that the study’s authors only simulated systems with two planets.