Dust and extinction in the planetary nebula NGC 7027

NGC 7027 is a well-observed dusty planetary nebula whose proximity and high surface brightness make it an ideal object for studying the distribution of optical and near-infrared emission at high spatial resolution. This paper presents high spatial resolution (≤ 1′.0 pixel^-1) optical and near-infrared images of NGC 7027 obtained to investigate the overall dust distribution and small-scale (∼ 1″-2″) extinction variation. Analysis of the derived near-infrared color excess suggests that the variation of line-of-sight visual extinction across the face of NGC 7027 ranges from ∼1 to 8 mag. Although the observed nebular size at near-infrared wavelengths is comparable to that determined at radio frequencies, indicating that the dust and ionized gas are partially comixed in the H II region, the dust component primarily responsible for the extinction (giving rise to the irregular morphological appearance of the nebula at wavelengths ≤ 2 μm) likely resides in a shell (or possibly a disk) outside of the volume containing the dust emitting the near-infrared thermal continuum.