Abstract :
Cometary research may give a clue to determine conditions in the solar nebula from chemical composition and structure of the nucleus. The composition of the cometary coma varies with heliocentric distance. It is assumed that the nucleus composition can be derived from analysis of the measured coma fluxes as a function of the orbital position.
Sublimation of minor gases from ices inside of a porous comet nucleus strongly depends on the chemical and physical parameters of the nucleus. Our model describing the gas and dust flux out of a porous nucleus has been used to study the influence of these parameters on the gas flux. For the presented study we solve the conservation equations for one major ice component H2O and several ices of higher volatility like CO, CH3OH, HCN, H2S, C2H2, C2H6, C3H4. Further, we assume different orientations of the spin axis and make some extreme assumptions on the composition and the structure of the nucleus to systematically analyze the resulting dust and gas fluxes. It was also found, that gas fluxes originate from a surface area around 40° latitude fit the measured data much better This could indicate, that the measured flux originate from active areas of higher latitudes.
