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Scientists have identified one of the mechanisms behind the formation of rogue planets – free-flying objects of planetary mass in space. The results of the study have been published on the arXiv preprint server.
They suggest that there are two possible ways in which rogue planets form. In the first scenario, the object is formed from a protoplanetary disk and then ejected from its home system due to interactions with a binary star, neighbouring planets, or when another star passes by the system. In the second scenario, they can be formed by the direct collapse of a clump of matter in a cloud of gas and dust.
In the new work, astronomers have used modelling to study the fate of circumstellar planets in binary systems. It turns out that binary systems are an efficient source of rogue planets. In simulations lasting 10 million years, each binary system ejects an average of two to seven planets with masses greater than one Earth mass. For giant planets with masses greater than 100 Earth masses, the number of ejected planets drops to 0.6 ejected planets per system.
In addition, significant differences were found between outliers ejected by planet-planet interactions and those ejected by binary stars. The velocity dispersion of planets ejected by binary interactions is about three times larger than the dispersion of planets ejected by gravitational scattering between planets.
Source arxiv.org
