Mysteriously massive planet orbits a small star
Published: Friday, Dec 1st 2023, 15:20
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The discovery of a new planet calls theoretical models of planet formation into question. The planet is far too large for its star, according to a new study by an international research team with Swiss participation.
The newly discovered planet, which orbits a so-called M-dwarf star called LHS 3154 with an orbit of 3.7 days, is around 13 times more massive than the Earth, according to the study published on Thursday in the scientific journal "Science". "Something that has never been observed before for a star with only 0.11 times the mass of the sun," wrote astronomer Frédéric Masset from the National University of Mexico in a commentary on the study published in the same journal.
According to the authors of the study, including a researcher from the Swiss Federal Institute of Technology (ETH) Zurich, current theories of planet formation cannot explain how such a massive planet could form around LHS 3154.
An unsolved mystery
An M dwarf star is the smallest and coolest type of star. Theories say that M dwarfs do not produce particularly large planets. Stars are formed from large clouds of gas and dust. The material left over from the star's formation process forms a disk around the star in which planets are later born.
According to theories, the amount of material in these disks around stars determines how massive the planets that form around them can be. And the amount of disk material depends largely on the mass of the star. So the smaller the host star, the smaller the planets around it should be.
According to the researchers' estimates in the study, the amount of dust in the disk around LHS 3154 must have been at least ten times greater than is typically found in disks around M-dwarf stars. They now want to find out in further studies exactly how this massive planet could have formed.
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