A 'rebellious' exoplanet orbits in the opposite direction of its star

A 'rebellious' exoplanet orbits in the opposite direction of its star. The study reveals that the planet GJ 3090 b, which orbits its star retrogradely, is the first such exoplanet around an M dwarf star. The research was conducted using NIRPS, a spectrograph at the La Silla Observatory, to measure the planet's orbital configuration. The planet's orbital plane is misaligned by approximately 136 degrees, which is significantly greater than the 70 degrees threshold for other misaligned systems. The absence of a massive companion to explain the orbit suggests that other hypotheses, such as the star accreted a misaligned, retrograde secondary disk, may be considered.

The study's findings are based on observations from the TESS space telescope, which detected GJ 3090 b. The planet has a radius of 2.2 times Earth's and a mass 4.5 times Earth's, making it a sub-Neptune. The research is published in the journal Astronomy & Astrophysics. The angle Psi for GJ 3090 b is approximately 136 degrees, which is the largest misalignment observed in a system with a massive companion. The study's authors suggest that the lack of a massive companion may indicate that the star's formation history is unique, and that the planet's retrograde orbit may be due to the star's formation process.

The research highlights the diversity of planetary systems and the complexity of exoplanet formation. The findings provide insights into the formation and evolution of planetary systems and may help in understanding the dynamics of planetary orbits. The study's results are important for future research on exoplanet systems and their formation mechanisms.

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