A Neptune-mass exoplanet in close orbit around a very low-mass star challenges formation models
Theories of planet formation predict that low-mass stars should rarely host exoplanets with masses exceeding that of Neptune. We used radial velocity observations to detect a Neptune-mass exoplanet orbiting LHS 3154, a star that is nine times less massive than the Sun. The exoplanet's orbital period is 3.7 days, and its minimum mass is 13.2 Earth masses. We used simulations to show that the high planet-to-star mass ratio (>3.5 × 10-3) is not an expected outcome of either the core accretion or gravitational instability theories of planet formation. In the core-accretion simulations, we show that close-in Neptune-mass planets are only formed if the dust mass of the protoplanetary disk is an order of magnitude greater than typically observed around very low-mass stars.
This is the author's version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science 382, 2023-12-01, doi: 10.1126/science.abo0233.
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Work Title | A Neptune-mass exoplanet in close orbit around a very low-mass star challenges formation models |
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License | In Copyright (Rights Reserved) |
Work Type | Article |
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Publication Date | November 30, 2023 |
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Deposited | February 02, 2024 |
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