Astronomers Find a Sub-Neptune Orbiting Completely Backward Around a Red Dwarf

Astronomers have discovered a sub-Neptune exoplanet, GJ 3090 b, orbiting a red dwarf star in the opposite direction to its parent star. The planet, which is 2.2 times the width of Earth and 4.5 times its mass, orbits its star once every 2.9 days. The researchers used the 3.6m telescope at the European Southern Observatory to study the planet's transit, looking for the Rossiter-McLaughlin effect. They found that the planet's orbit is retrograde, with an obliquity of around 136 degrees, which is much higher than typical for planets in our solar system. This suggests that the planet's orbit is not caused by gravitational interactions with other planets or stars, as is usually the case for retrograde exoplanets.

• "GJ 3090 b is the smallest exoplanet to have its orbital obliquity mapped around a red dwarf."
• "The researchers suspect another planet in the system might be retrograde, but there is not enough data to confirm this."
• "The discovery challenges current theories of planet formation, suggesting a primordial disk flip might have occurred after the star formed."
• "Astronomers have observed 'Peter Pan disks' that last longer than expected, which could explain the planet's retrograde orbit."

This finding has major implications for our understanding of planet formation and the role of interstellar material in shaping planetary orbits. The discovery highlights the complexity of exoplanet systems and the need for advanced observational techniques to study them. It also opens the door to future research on other retrograde exoplanets and the processes that might have led to their formation.

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