Resolved Mid-Infrared Emission in the Narrow-Line Region of NGC 4151

We present subarcsecond-resolution mid-infrared images of NGC 4151 at 10.8 and 18.2 μm. These images were taken with the University of Florida mid-IR camera/spectrometer OSCIR at the Gemini North 8 m telescope. We resolve emission at both 10.8 and 18.2 μm, extending ~3.″5 across at a P.A. of ~60°. This coincides with the narrow-line region of NGC 4151, as observed in [O III] by the Hubble Space Telescope. The most likely explanation for this extended mid-IR emission is dust in the narrow-line region heated by a central engine. We find no extended emission associated with the proposed torus and place an upper limit on its mid-IR size of ≲35 pc.