Carbon stars tend to be cool giants (although dwarf carbon stars are known) with greatly enhanced bands of molecules involving carbon. Especially prominent in most carbon stars are the Swan bands of C2. Some carbon stars also show enhancements of the G-band (CH) and the CN bands. These two carbon stars show strong lines of barium and strontium, both s-process elements. It is thought that the excess carbon and s-process elements seen in the atmospheres of carbon stars are due to deep convection currents which dredge nuclear-processed material up from the core.
This figure uses 3.6 Å resolution flux spectra.