LAUSR

In order to improve the physical interpretation about innermost dusty regions in protoplanetary discs around brown dwarf (BD), and even very low mass star (VLMS), we present a grid of models taking into account two different sets: (i) The set called standard model, that simulates an axisymmetric dusty disc with an inner curved wall. (ii) The perturbed one called non-standard where the axisymmetry of the inner edge has been broken. We have achieved a fitting for the disc structure able to explain the spectral energy distribution (SED). As the main condition, we assume that the changes of the inner wall geometry in the tongue-like shape depend on the Rayleigh–Taylor instability (R-TIns) generated in the inner disc edge. For each object, we parametrize the shape of the inner wall to find a time-dependent model that enables us to explain the photometric near-Infrared variability and connect the changes on the inner disc structure with the amplitude of such variability. We re-analysed photometric measurements from near to mid-infrared wavelengths of a sample of 6 BDs and one VLMS in different cloud associations which were previously studied by other authors. We also show that the flux change calculated between the non-standard and the standard configurations models the observed variability in LRLL 1679. The magnitude changes due to these fluctuations slightly depend on the wavelength and they can present differences of up to 0.9 mag. We suggest that if the R-TIns persist enough time, the features in the protoplanetary inner disc, e.g. inner holes or gaps evolve.