2001ApJ...557L.117U

We present high-sensitivity near-IR images of a carbon-rich proto-planetary nebula, AFGL 618, obtained with the Subaru Telescope. These images have revealed ``bullets'' and ``horns'' extending farther out from the edges of the previously known bipolar lobes. The spatial coincidence between these near-IR microstructures and the optical collimated outflow structure, together with the detection of shock-excited, forbidden IR lines of atomic species, strongly suggests that these bullets and horns represent the locations from which [Fe II] IR lines arise. We have also discovered CO clumps moving at greater than 200 km.s^–1 at the positions of the near-IR bullets by reanalyzing the existing ¹²CO J=1-0 interferometry data. These findings indicate that the near-IR microstructures represent the positions of shocked surfaces at which fast-moving molecular clumps interface with the ambient circumstellar shell.