LHS 3154 b
LHS 3154 b is a Neptune-sized exoplanet orbiting the red dwarf LHS 3154. It is located about 50 light-years from Earth, in the constellation of Hercules. As it is a massive planet that orbits very close to a low-mass star, it is challenging current models about exoplanet formation, as it would require 10 times more mass than there was in the protoplanetary disk where the planet formed.
Characteristics
LHS 3154 b is a Neptune-like exoplanet with a minimum mass of 13.2 and an estimated radius of 3.65. It orbits its parent star at a distance of, and completes one revolution every 3 days and 17 hours.Importance
The discovery of LHS 3154 b raises doubts about the formation of planets, challenging current planetary models, because such a massive planet was not expected to orbit such a small star, with just a ninth the mass of the Sun, and currently it is the only short-period Neptune-mass planet to orbit a low mass star. Although there are more massive exoplanets orbiting red dwarfs, such as TZ Arietis b and GJ 3512 b, they have wide orbits, with periods longer than 200 days, and likely formed in a different way than LHS 3154 b, such as gravitational instability within a massive gaseous outer disk.One of the ways in which planets form is through core accretion, where they form from initial cores that accrete dust and gas. Planets formed from core accretion orbiting low-mass stars should have a maximum mass of 5. LHS 3154 b, however, with a minimum mass of 13, presents a challenge to this theory.
Suvrath Mahadevan, one of the planet's discoverers, says: "The planet-forming disk around the low-mass star LHS 3154 is not expected to have enough solid mass to make this planet. But it’s out there, so now we need to reexamine our understanding of how planets and stars form.". According to Guðmundur Stefánsson, another discoverer of the planet, the recent discovery of LHS 3154 b creates doubts about the formation of planets around less massive stars, as it was previously believed that only terrestrial planets could form around these stars.