Discovery of magnetic field variations with the 12.1-minute pulsation period of the roAp star (gamma) Equulei

We present evidence of X-ray rotational modulation on VXR45, a young fast rotator star, member of IC 2391. It is a dG9 spectral type star whose rotational period and X-ray luminosity make it a supersaturated star. Our X-ray observation, made with EPIC/PN on XMM-Newton, covers about two photometric rotational periods. The detection of X-ray rotational modulation implies the presence of structural inhomogeneities. Possible interpretations are presented and discussed.