A “tsunami” in the protoplanetary disk of SV Cep

Abstract

The results of ~15 years of photometric observations of the UX Ori star SV Cep in the near-infrared (JHKL) are presented. They demonstrate the presence of a cyclic component with a period of ~7 years in the variations of the IR fluxes. This is clearly seen in all four IR bands, but is absent in the optical. The variation amplitude is highest in the K band: ΔK ≈ 0.68m. The shape of the variations differs slightly in the transition from J to L. However, it is reproduced with good accuracy during two cycles, suggesting a periodic process is observed. If the periodic perturbations in the circumstellar disk of SV Cep are due to a companion’s orbitalmotion, the orbital semi-major axis should be ~5AU, foramass of SVCep of 2.6M⊙. The absence of a seven-year period in the optical light curve of SV Cep means that the observed period cannot be due to variations in the circumstellar extinction. The IR brightness variations could be due to the companion’s motion along an eccentric orbit, resulting in a periodic modulation of the rate of accretion onto the star.