New exoplanet challenges formation theories

The study notes that M-class dwarf stars, like "LHS 3154," are the smallest and coldest type compared to other stars. They form from large clouds of gas and dust, with remaining materials creating a disk around the star that forms planets. The amount of matter in these disks, largely dependent on the star's mass, determines the size of the resulting planets. M-class dwarf stars, common in the Milky Way Galaxy, typically host smaller, rocky planets rather than gas giants.

The study highlighted that LHS 3154b, completing its orbit around the small, cool star "LHS 3154" in 3.7 Earth days, could be the largest planet discovered in a close orbit around such a star. Penn State University Professor of Astronomy and Astrophysics, Suvrath Mahadevan, emphasized the unexpected nature of finding such a heavy planet around a low-mass star, indicating a need to reevaluate our understanding of planet and star formation.

The research team examined "LHS 3154b" using HPF, designed to detect planets in habitable zones around small, cool stars that could support liquid water and, consequently, life. Their modeling and analysis suggested that the planet's heavy core would require more solid matter in the disk than previously thought possible around such a star.

Megan Delamer, a co-author of the study and a graduate student in astronomy, stated that current theories of planet formation struggle to explain these findings. She suggested that the celestial body discovered might be exceedingly rare.

The research was published in the journal Science.