Scientists at Pennsylvania State University have reported the discovery of a planet that is too large for its host star. Their existence cannot be explained by classical models of planet formation, according to a study published in the journal Science. Exoplanet LHS 3154b was discovered using the Habitable Zone Planet Finder (HPF) spectrometer, which is designed to look for planets orbiting the coldest stars that may have liquid water on their surfaces. Ta. These planets are much closer to their parent stars than Earth or the Sun. The short distance and low mass of the cold star causes a large Doppler shift in the star’s emission, indicating the presence of a planet.

LHS 3154b is about the size of Neptune, 13 times more massive than Earth, and orbits LHS 3154, an ultracool dwarf star nine times more massive than the Sun. The orbital period of the exoplanet is 3.7 days. The mass ratio of this exoplanet to its parent star is more than 100 times greater than that of the Earth and the Sun. Stars form from large clouds of gas and dust, from which protoplanetary disks also form. The disk around low-mass star LHS 3154 is not expected to contain enough material to form such a large planet. The existence of LHS 3154b cannot be explained by either accretion or gravitational instability scenarios. Models show that Neptune-like planets can only form if the dust mass in the protoplanetary disk is an order of magnitude greater than what is typically observed for very low-mass stars. . The accretion scenario assumes that the growth of a planet’s core occurs through accretion of material as it passes through the protoplanetary disk environment. According to the gravitational instability scenario, the region with the most material accumulation will exert a greater gravitational influence on neighboring regions and attract a large amount of surrounding material. The first option explains the formation of rocky planets, and the second explains the formation of gas giant planets.

sourc: https://www.science.org/doi/10.1126/science.abo0233