Westbrook's molecular gun: Discovery of near-infrared microstructures in AFGL 618

We present high-sensitivity near-IR images of a carbon-rich proto-planetary nebula, AFGL 618, obtained with the Subaru Telescope. These images have re vealed "bullets" and "horns" extending farther out from the edges of the pr eviously known bipolar lobes. The spatial coincidence between these near-IR microstructures and the optical collimated outflow structure, together wit h the detection of shock-excited, forbidden IR lines of atomic species, str ongly suggests that these bullets and horns represent the locations from wh ich [Fe ii] IR lines arise. We have also discovered CO clumps moving at gre ater than 200 km s(-1) at the positions of the near-IR bullets by reanalyzi ng the existing (CO)-C-12 J = 1-0 interferometry data. These findings indic ate that the near-IR microstructures represent the positions of shocked sur faces at which fast-moving molecular clumps interface with the ambient circ umstellar shell.