A quarter of sun-like stars feed on their planets

A quarter of sun-like stars feed on their planets
A quarter of sun-like stars feed on their planets

In the 32 years since planets orbiting stars other than our Sun were first discovered, we have found that planetary systems are commonplace in the Galaxy. However, many of them are very different from the known solar system.

The planets in the solar system revolve around the star along a stable and almost circular trajectory, which suggests that the orbits of the planets have not changed much since their formation. But many planetary systems orbiting other stars have suffered from a very chaotic past.

The relatively calm history of our solar system has contributed to the prosperity of life on Earth. In the search for alien worlds that may contain life, we can narrow down our targets if we have a way to identify systems that had the same peaceful past, researchers from Monash University write.

Astronomers looked at this question and found that 20% to 35% of stars like the Sun feed on their own planets - with the most likely figure being 27%. This suggests that at least a quarter of the planetary systems orbiting stars similar to the Sun had a very chaotic and dynamic past.

Scientists have recorded several exoplanetary systems in which large or medium planets moved significantly. The gravity of these migrating planets could also disrupt the trajectories of other planets or even push them into unstable orbits.

According to the researchers, it was not easy to come to such conclusions. For this, it was necessary to study the chemical composition of stars in binary systems. They are made up of two stars orbiting each other and usually formed at the same time from the same gas, so scientists expect them to contain the same mixture of elements.

However, in some cases this does not happen, and the researchers believe that this is due to the absorption of planets by the stars, which change the chemical composition of the star.

Researchers have studied the chemical composition of 107 binary systems of stars similar to the Sun by analyzing the spectrum of light they emit. From this, they determined how many stars contain more planetary material than their companion star.

Scientists have also found three things that add up to unequivocal evidence that the chemical differences observed between the binary pairs were caused by the eating of planets.

First, stars with a thinner outer layer were more likely to be richer in iron than their companion. This is consistent with the version of the absorption of the planets.

Second, stars that are richer in iron and other elements of rocky planets also contain more lithium than their satellites. Lithium quickly decays in stars, but remains in planets.

Third, stars that contain more iron than their satellites have a standard carbon content, which is a volatile element and therefore cannot be carried by rocks. Consequently, these stars were chemically enriched with planetary rocks or planetary material.

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