The Dust Sublimation Region of the Type 1 AGN NGC 4151 at a Hundred Microarcsecond Scale as Resolved by the CHARA Array Interferometer

The nuclear region of Type 1 AGNs has only been partially resolved so far in the near-infrared (IR) where we expect to see dust sublimation and nucleus directly without obscuration. Here present near-IR interferometric observation brightest AGN NGC4151 at long baselines ~250 m using CHARA Array, reaching structures hundred micro-arcsecond scales. squared visibilities decrease down as low ~0.25, definitely showing that structure is resolved. Furthermore, combining with previous visibility measurements shorter but different position angles, show elongated *perpendicular* polar axis nucleus, defined by optical polarization a linear radio jet. A thin-ring fit gives minor/major ratio ~0.7 radius ~0.5 mas (~0.03 pc). This consistent case sublimating grains are distributed preferentially an equatorial plane ring-like geometry, viewed inclination angle ~40 deg. Recent mid-IR finding polar-elongated geometry pc scale, together larger-scale outflow spectrally HST, would generally suggest dusty, conical hollow being launched presumably region. might potentially lead morphology near-IR, opposed results here. We discuss possible scenario episodic, one-off anisotropic acceleration formed polar-fast equatorially-slow velocity distribution, having effectively flaring observe.