About 30 years ago, scientists were not sure if there were planets outside our Solar system at all, and now more than 5 thousand of them have been discovered. During the analysis, scientists found a strange pattern – the absence of exoplanets of a certain size. Astronomers are more likely to discover rocky super-Earths that are about 1.4 times wider than our planet, or watery “mini-Neptunes” that are 2.4 times larger. Exoplanets of intermediate size are practically not found. A new model published in Astrophysical Journal Letters offers to explain why this is the case. As it turns out, it’s all about destroying them.
Interplanetary collisions
The prevailing hypothesis about this gap suggests that smaller planets have tended to approach their stars over time. At the same time, they were heated so much that, in fact, they burned to a “crisp”.
However, a group of astrophysicists from Rice University in Texas published a journal article explaining their own theory. Instead of burning up, small exoplanets can be involved in terrifying interplanetary collisions that destroy them, and from the wreckage of these catastrophes, large exoplanets are then formed.
According to the lead author of the study, Andre Isidora, the new theory is based on the understanding that smaller rocky planets approach their stars over time, their orbits become more unstable, which leads to their potential collision.
Theory Check
According to Rice researchers’ simulations, two rocky planets colliding with each other would increase their total mass. But since they would lose layers of gas or water in doing this, it would also reduce their radii and cause them to form one more massive planet – either a super-Earth or a mini-Neptune.
Earlier we reported on the amazing exoplanets discovered in 2022.
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