Massive planet too big for its own sun pushes astronomers to rethink exoplanet formation

The planet, named LHS 3154b, is more than 13 times the mass of Earth but orbits a star that is only nine times less massive than the Sun. This is a much higher mass ratio than any other known exoplanet system.

LHS 3154b is a gas giant, like Jupiter, but it is much closer to its star than any other known gas giant. It orbits its star every two days, at a distance of only 1 million kilometers.

The discovery of LHS 3154b was made using the Habitable Planet Finder (HPF), a spectrograph at the Penn State University Observatory.


Astronomers are still trying to figure out how LHS 3154b formed. One possibility is that the planet formed in a disk of gas and dust around the star, just like other planets.

Another possibility is that LHS 3154b formed in a different way, perhaps by colliding with another planet or by being captured from another star system. However, these scenarios are also difficult to explain.

The discovery of LHS 3154b is a major puzzle for astronomers. It is forcing them to rethink their understanding of how planets form and how solar systems evolve.


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