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Session 6 - Novae and Supernovae.
Display session, Monday, June 08
Atlas Ballroom,
Infrared and visible observations of classical novae show that these objects are associated with substantial dust shells. The time variability of novae makes them ideal candidates for time-dependent modeling. Past models of nucleation and grain growth in novae have not successfully reproduced the grain sizes observed in these objects. The interplay of the harsh radiation field, density inhomogeneities in the ejecta, and the photochemistry of small carbonaceous molecules in determining the grain formation rate is still not well understood. We have applied the kinetic nucleation theory to study the formation and growth of dust grains in the nova environment. Grain formation is modeled using kinetic equations for small cluster growth coupled to moments of the grain size distribution to determine the growth of larger particles. We consider the effects of photodissociation and sticking probability. The dust formation stage of the novae outflow produces a blackbody spectrum which can be used to infer the grain sizes in the ejecta. To compare our model results with observations, a radiative transfer model is applied to a dust shell with a grain size distribution determined in our grain formation model. We examine how dust production in our models varies with the luminosity and mass loss of the nova. Using novae observations as constraints, we place limits on the grain nucleation rate required to match the model results with observations.
