Optical imaging and spectroscopy of the impact plumes on Jupiter.

During the period July 15th - July 22nd the authors obtained narrow-band images of Juptier at wavelengths using the 1-m Jacobus Kapteyn Telescope on La Palma. On July 19th - 21st they also obtained low and intermediate resolution spectroscopy of the impact sites using the 2.5 m Isaac Newton Telescope. A subset of the images obtained on the 19th July clearly show the evolution of the plume resulting from the impact of fragment L. At the same time the authors observed the associated emission-line spectrum at wavelengths 3500 Å - 6600 Å. The spectra demonstrate the existence of neutral Na, Fe, Mg, Ca and Mn in the plume, which the authors identify as remnants of the vapourised bolide. The following night they also obtained high-resolution spectra of the Na D doublet in the plume resulting from the impact of fragment Q1. The authors observe evidence for both the cold optically thin plume material and also the warm optically thick fallback region.