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Properties of free floating planets originating in circumbinary planetary systems

Presentation #614.04 in the session Planets in and around Binary Stars.

Published onApr 03, 2024
Properties of free floating planets originating in circumbinary planetary systems

In recent years, free floating planets, i.e. those planets not found to be in a planetary system and with no observable companions, have begun to be found in microlensing and direct imaging surveys. Observations have shown that they have a wide variety of masses, ranging from terrestrial-like to giant planets. Microlensing surveys predict that there could be on order tens of free floating planets per star in the Milky Way. How these planets form and arrive on their observed trajectories remains a very open and intriguing question. Whilst there are many mechanisms for forming free floating planets, e.g. ejections from planet-planet interactions or gravitational collapse of gas within molecular clouds, very few models have predicted the properties of free floating planets on a global scale. In this presentation I will present the outcomes of state-of-the-art circumbinary planet formation models, that naturally produce countless examples of free floating planets. I will show the arising velocity dispersions, relevant for direct imaging analysis, and mass distributions that can be gleaned from microlensing surveys. I will compare the effects of the local star forming environment, the strength of turbulence in circumbinary discs, and the separation of the circumbinary stars themselves, on the distributions of these observable properties. Finally I will show the differences that arise between free floating planets ejected through interactions with binary stars, to those that are ejected by planet-planet interactions, akin to those that would form in singular stars systems. Ultimately these results will be able to provide testable observables that with sufficient observations, it would be possible to further understand the formation and evolution of these exotic worlds.

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