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(Aims) Near-infrared imaging polarimetry at high-angular resolutions hasrevealed intriguing distribution of circumstellar dust towards FU Ori-typeobjects (FUors). These dust grains are probably associated with either anaccretion disk or an infalling envelope. Follow-up observations in themid-infrared would lead us to a better understanding of the hierarchy of themass accretion processes onto FUors (i.e., envelope and disk accretion), whichhold keys for understanding the mechanism of their accretion outbursts and thegrowth of low-mass young stellar objects in general. (Method) We have developeda semi-analytic method to estimate the mid-infrared intensity distributionsusing the observed polarized intensity (PI) distributions in H-band(lambda=1.65 micron). We have derived intensity distributions for two FUors, FUOri and V1735 Cyg, at three wavelengths (lambda=3.5/4.8/12 micron) for variouscases, i.e. with a star or a flat compact self-luminous disk as an illuminatingsource; an optically thick disk or an optically thin envelope for circumstellardust grains; and three different dust models. (Results) We have been able toobtain self-consistent results for many cases and regions, in particular whenthe viewing angle of the disk/envelope is zero (face-on). Our calculationssuggest that the mid-infrared extended emission at the above wavelengths isdominated by the single scattering process. The contribution of thermalemission is negligible unless we add an additional heating mechanism such asadiabatic heating in spiral structures and/or fragments. The uncertain natureof the central illuminating source, the distribution of circumstellar dustgrains and the optical properties of dust grains yield uncertainties in theintensity levels on orders of magnitude, e.g., 20-800, for the disk/envelopeaspect ratios of ~0.2 and lambda=3-13 micron.

Semi-analytic calculations for extended mid-Infrared emission associated with FU Ori-type objects