Physicochemical conditions in a cometary coma

Temperature plays an important role in the modelling of chemical pathways in the interstellar medium and must be modelled correctly for the comet. The energy balance is similar to that for all bodies orbiting a star and we will return to the ideas for the planets later. The energy balance considerations for an orbiting body are  

The recent close-encounter, especially with comet Hale-Bopp, focused the attention of the ground-based telescopes in all regions of the electromagnetic spectrum to produce the molecular inventory shown in Table 6.4. Chemical network models for 

Adapted with permission from Bockelee-Morvan et al. (2002). Technique of observation. b Abundance given for nuclear + extended source. c Measured at = 2.9 AU. d Abundance given for extended source. e Probably a daughter species. 

Clearly some molecular processing occurs in the coma to produce larger molecules such as methanol, formaldehyde and more complex still, but the detection and identification of bigger molecules are limited by the sensitivity and resolution of the instruments. The inventory, however, is probably a guide to an untold story 

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