Rapid dust formation in novae:the speed-class formation timescale correlation eplained

Williams, S. C. and Bode, M. F. and Darnley, M. J. and Evans, A. and Zubko, V. and Shafter, A. W. (2013) Rapid dust formation in novae:the speed-class formation timescale correlation eplained. Astrophysical Journal Letters, 777 (2). ISSN 2041-8205

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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 between 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 short-ward of the Lyman limit. The rate at which the spectrum evolves also depends on the speed class. We have therefore refined the simple model by assuming photons at energies higher than the Lyman limit are absorbed by neutral hydrogen gas internal to the dust formation sites, therefore preventing these photons reaching the nucleation sites. With this refinement the dust formation timescale is theoretically dependent on speed class and the results of our theoretical modification agree well with the observational data. We consider two types of carbon-based dust, graphite and amorphous carbon, with both types producing similar relationships. Our results can be used to predict when dust will form in a nova of a given speed class and hence when observations should optimally be taken to detect the onset of dust formation.

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Journal Article
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Astrophysical Journal Letters
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This is an author-created, un-copyedited version of an article accepted for publication/published in Nanotechnology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi:10.1088/2041-8205/777/2/L32
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28 Jan 2016 08:58
Last Modified:
16 Sep 2023 01:16