Modelling simultaneous CoRoT and Spitzer light curves: the impact of bending waves in the inner disc

Abstract

ABSTRACT We present a physical interpretation of the amplitude of light curves of young stellar objects (YSOs) simultaneously observed in the infrared with the Spitzer Space Telescope and in the optical with the CoRoT satellite. The modelled objects come from a sample of YSOs in the star forming region NGC 2264, and we focus on a subsample showing periodic dips in their CoRoT light curves. The model includes emission and stellar occultation caused by a warp at the inner edge of the disc. In order to fit the observed fluxes, we add a contribution coming from the inner disc. We find that the disc flux signal has the same periodicity as the stellar rotation, with a phase offset between the stellar and the disc signal of half the period, that is, the peak of the former coincides with the minimum of the latter. This behaviour is consistent with MHD simulations where a bending wave appears opposite to the warp formed at the base of the magnetospheric stream, which is rotating with the stellar rotation period. This evidence highlights the importance of infrared observations to complement the information extracted from optical light curves to be able to characterize structures at the inner disc.