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Paper: Rapid Dust Formation in Novae: Speed Class and Grain Formation Timescale
Volume: 490, Stella Novae: Past and Future Decades
Page: 255
Authors: Williams, S. C.; Bode, M. F.; Darnley, M. J.; Zubko, V.; Evans, A.; Shafter, A. W.
Abstract: Observations show that the time of onset of dust formation in classical novae depends strongly on their speed class, with dust typically taking longer to form in slower novae. Using empirical relationships of speed class, luminosity and ejection velocity, it can be shown that dust formation timescale is expected to be essentially independent of speed class. However, following a nova outburst the spectrum of the central hot source evolves, with an increasing proportion of the radiation being emitted blue-wards of the Lyman limit. The rate at which the spectrum evolves depends on the speed class. We have therefore refined the simple model by assuming photons at wavelengths shorter than the Lyman limit are absorbed by neutral hydrogen gas internal to the dust formation sites. We find that the dust formation timescale is then dependent on speed class and the predicted relationship agrees well with the observations.
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