Stars stably accreting from substellar objects
Abstract
Substellar objects such as brown dwarfs and planets are generally expected to remain detached from their main-sequence host stars unless orbital decay or stellar expansion brings them into contact, leading to rapid engulfment and destruction. Such a fate is predicted for the Earth and other rocky planets in our solar system; however, in certain cases, theory also allows for stable long-lived mass transfer from a substellar object onto its main-sequence host, though such accretion has never been directly observed. Here we report the first direct observations of stable mass transfer from a substellar object onto a main-sequence star. In particular, we identify two binaries, ZTF J0440+2325 and ZTF J1444+4820, with orbital periods of just 87 and 67 minutes, respectively, in which a brown dwarf stably transfers mass onto an M dwarf companion. These systems demonstrate that the fate of some substellar objects is not rapid engulfment and destruction, but instead gradual consumption for potentially billions of years.
Cite
@article{arxiv.2603.17039,
title = {Stars stably accreting from substellar objects},
author = {Aaron Householder and Kaitlyn Shin and Kevin B. Burdge and Thomas R. Marsh and Saul A. Rappaport and Kareem El-Badry and Joheen Chakraborty and Emma Chickles and Fei Dai and Matthew J. Graham and S. R. Kulkarni and Pablo Rodríguez-Gil and Andrew Vanderburg and Samuel Whitebook},
journal= {arXiv preprint arXiv:2603.17039},
year = {2026}
}
Comments
29 pages, 10 figures (3 main + 7 extended data), 1 table. Submitted to Nature Astronomy