In:
Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 530, No. 3 ( 2024-04-25), p. 3500-3513
Abstract:
One of the leading mechanisms invoked to explain the existence of the radius valley is atmospheric mass-loss driven by X-ray and extreme-ultraviolet irradiation, with this process stripping the primordial envelopes of young, small planets to produce the observed bimodal distribution. We present an investigation into the TOI-431 and ν2 Lupi planetary systems, both of which host planets either side of the radius valley, to determine if their architectures are consistent with evolution by the X-ray/ultraviolet (XUV) mechanism. With XMM–Newton, we measure the current X-ray flux of each star, and see evidence for a stellar flare in the TOI-431 observations. We then simulate the evolution of all of the transiting planets across the two systems in response to the high-energy irradiation over their lifetimes. We use the measured X-ray fluxes as an anchor point for the XUV time evolution in our simulations, and employ several different models of estimating mass-loss rates. While the simulations for TOI-431 b encountered a problem with the initial calculated radii, we estimate a likely short (∼Myr) timespan for primordial envelope removal using reasonable assumptions for the initial planet. ν2 Lupi b is likely harder to strip, but is achieved in a moderate fraction of our simulations. None of our simulations stripped any of the lower density planets of their envelope, in line with prediction. We conclude that both systems are consistent with expectations for generation of the radius valley through XUV photoevaporation.
Type of Medium:
Online Resource
ISSN:
0035-8711
,
1365-2966
DOI:
10.1093/mnras/stae1054
Language:
English
Publisher:
Oxford University Press (OUP)
Publication Date:
2024
detail.hit.zdb_id:
207232-4
detail.hit.zdb_id:
2016084-7
SSG:
16,12
