Hot graphite dust in the inner regime of NGC 4151

We model the near infrared SED of NGC 4151 with a 3-D radiative transfer SKIRT code, using which torus only (TO) and Ring And Torus (RAT) scenarios are studied. In RAT models, graphite ring-like structure (clumpy or smooth), is incorporated between accretion disk. vary inclination angle $(i)$, inner radius (of ring, $R_{\rm in, t}$ r}$ respectively), half-opening ($\sigma $), optical depth ($\tau_{9.7, \rm t} $ $\tau_{9.7, r} ring ) dust clump size ($R_{\rm clump}$). perform statistical analysis parameter space find that all models able to explain flat NIR minor differences in derived parameters. For TO model, we get, t}=0.1$ pc, $\sigma = 30^\circ $, $i 53^\circ t}=10$ clumpsize, clump}$ =0.4 pc. smooth r}=0.04$ total}$ 11 for clumpy 0.04$ pc/0.06 pc total}=20$. The from does not agree observations ($\sim pc). Hence, most likely scenario hot located at distance 0.04 centre, composed distribution followed by dusty 0.1 ISM type grains.