An extreme test case for planet formation: a close-in Neptune orbiting an ultracool star
Abstract
In current theories of planet formation, close-orbiting planets as massive as Neptune are expected to be very rare around low-mass stars. We report the discovery of a Neptune-mass planet orbiting the `ultracool' star LHS 3154, which is nine times less massive than the Sun. The planet's orbital period is 3.7 days and its minimum mass is 13.2 Earth masses, giving it the largest known planet-to-star mass ratio among short-period planets (\,100 days) orbiting ultracool stars. Both the core accretion and gravitational instability theories for planet formation struggle to account for this system. In the core-accretion scenario, in particular, the dust mass of the protoplanetary disk would need to be an order of magnitude higher than typically seen in protoplanetary disk observations of ultracool stars.
Keywords
Cite
@article{arxiv.2303.13321,
title = {An extreme test case for planet formation: a close-in Neptune orbiting an ultracool star},
author = {Gudmundur Stefansson and Suvrath Mahadevan and Yamila Miguel and Paul Robertson and Megan Delamer and Shubham Kanodia and Caleb Cañas and Joshua Winn and Joe Ninan and Ryan Terrien and Rae Holcomb and Eric Ford and Brianna Zawadzki and Brendan P. Bowler and Chad Bender and William Cochran and Scott Diddams and Michael Endl and Connor Fredrick and Samuel Halverson and Fred Hearty and Gary J. Hill and Andrea Lin and Andrew Metcalf and Andrew Monson and Lawrence Ramsey and Arpita Roy and Christian Schwab and Jason Wright and Gregory Zeimann},
journal= {arXiv preprint arXiv:2303.13321},
year = {2023}
}
Comments
Original Manuscript as submitted to Science on Oct 17, 2022. In review