  Young stars exhibit variability due to changes in the gas accretion rate onto
them, an effect that should be quite significant in the early stages of their
formation. As protostars are embedded within their natal cloud, this
variability may only be inferred through long wavelength observations. We
perform radiative transfer simulations of young stellar objects (YSOs) formed
in hydrodynamical simulations, varying the structure and luminosity properties
in order to estimate the long-wavelength, sub-mm and mm, variations of their
flux. We find that the flux increase due to an outburst event depends on the
protostellar structure and is more prominent at sub-mm wavelengths than at mm
wavelengths; e.g. a factor of 40 increase in the luminosity of the young
protostar leads to a flux increase of a factor of 10 at 250 micron but only a
factor of 2.5 at 1.3 mm. We find that the interstellar radiation field dilutes
the flux increase but that this effect may be avoided if resolution permits the
monitoring of the inner regions of a YSO, where the heating is primarily due to
protostellar radiation. We also confirm that the bolometric temperature and
luminosity of outbursting protostars may result in an incorrect classification
of their evolutionary stage.
