Detection of CH+, CH and H2Molecules in the Young Planetary Nebula IC 4997Based on observations obtained with The Nordic Optical Telescope and The Harlan J. Smith Telescope.

We have detected CH+and CH molecular absorption lines from the youngcompact planetary nebula IC 4997 from high resolution optical spectra. A high-resolution infra-red (Hand Kbands) spectrum provides detection of H2emission lines among many other lines. The H2lines provide an excitation temperature of 2100 K which may result from UV fluorescence in the envelope or from shocks formed at the interface between an expanding outflow of ionized gas and the neutral envelope ejected when the star was on the AGB. It is suggested that the CH+may result from the endothermic reaction C + H2? CH++ H. Intriguingly, CH+and also CH show a higher expansion velocity than H2emission suggesting they may be part of the post-shocked gas.