Jeremy Couturier

2019-2022
All over the World

The co-orbital motion

My PhD was dedicated to the study of the co-orbital motion. This type of motion occurs when two celestial objects, that can be planets around a star or satellites around a planet, share the same orbit. Specifically, my work consisted in understanding what was the long-term behaviour of these systems when they can be deformed by tides. I published two first-authors papers on the subject, available in the tab Publications. You can read here a vulgarization article (in French) about my first paper.

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One astonishing fact is that among the thousands of discovered exoplanets, none are in a co-orbital motion around their star. In my first paper, we build an analytical model dedicated to the study of two exoplanets orbiting a star. We give a proof that these system are always destroyed by tides, which explains why no exoplanets was discovered co-orbital to another. An article of scientific vulgarization, in French, is available here.

Resonance chains refer to planetary systems where mean-motion resonances exist between the different planets. In my second work, we study a co-orbital pair of exoplanets embedded in a resonance chain, and we show that the chain increases the time before destruction by tidal forces. This work hence increases the chance of a future detection of co-orbital exoplanets

One example of co-orbital system is given by the pair of Saturnian moons Janus and Epimetheus, which are co-orbital to Saturn. The hand-made image at the top of this page gives a representation of this system. Although the image is obviously not a real one, it is made up of real images, downloaded on the website of the NASA.

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