The dipper light curve of V715 Persei: is there dust in the magnetosphere?

Abstract

Context. The dipper optical light curves in young stellar objects are commonly interpreted as partial or total occultation of the stellar radiation by dust surrounding the star. Aims. In this work, we analyze the amplitude of the optical light curve of V715 Per, located in the young star forming region IC 348. Observations gathered over the years suggest that the light curve can be explained by dust extinction events. Methods. In our model, the dust is distributed inside the magnetosphere according to the strength of the stellar magnetic field. The dust distribution is modulated by the vertical component of the field whose axis is misaligned with respect to the rotational axis. We include a model for evaporation of the dust reaching the magnetosphere in order to consistently calculate its distribution. Results. For V715 Per, there is dust in the optically thick warp at the disk truncation radius. We suggest that the optical light curve is explained by extinction caused by dust reaching inside the magnetosphere. The dust distribution is optically thin, and it cannot survive for a long time because of the high temperature and low density. However, as the grains rapidly move towards the stellar surface and the sublimation is not instantaneous, there is a layer of dust covering the magnetosphere responsible for the extinction. Conclusions. Dust surviving the harsh conditions of the magnetospheric accretion flow may be responsible for some of the dipper light curves.