Different orbital evolutions for a planet with 1 ≤ M_plin/M_J ≤ 10 and 0.02 ≤ a_in (AU) ≤ 0.1 computed for Ω_in = 3.2 Ω_⊙ (top panel), Ω_in = 5 Ω_⊙ (middle panel), and Ω_in = 18 Ω_⊙ (bottom panel). The salmon-coloured hatched area shows the parameter space for which, after the engulfment, it is possible to reproduce the rotational period and X-ray luminosity of GJ 504 when considering the largest age uncertainty. The lime-hatched area indicates a subset of the salmon-hatched area, for the smaller age uncertainty. The grey shaded area shows the region below the Roche limit.