Revisiting Kepler-444

Context. Kepler-444 is one of the oldest planetary systems known thus far. Its peculiar configuration consisting five sub-Earth-sized planets orbiting companion to a binary stellar system makes its early history puzzling. Moreover, observations HI-Ly α variations raise many questions about potential presence escaping atmospheres today. Aims. We aim study orbital evolution Kepler-444-d and Kepler-444-e impact atmospheric evaporation on Kepler-444-e. Methods. Rotating models Kepler-444-A were computed with Geneva code coupled an code, accounting for effects dynamical, equilibrium tides evaporation. The impacts multiple rotational histories X-ray extreme ultraviolet (XUV) luminosity evolutionary tracks are explored. Results. Using detailed rotating able reproduce rotation rate Kepler-444-A, we find that observed perfectly in line what expected this old K0-type star, indicating there no reason it be exceptionally active as would required explain from origin. show given low mass (~0.03 M ⊕ ) relatively large distance (~0.06 AU) e, dynamical negligibly affect their orbits, regardless considered. point out instead how remarkable estimation lifetime loss that, even case extremely slow seems unlikely such planet could retain fraction initial water-ice content if assume formed Ganymede-like composition.