| Abstract : | Novae are the only objects in which it has been possible to observe directly all aspects of circumstellar grain formation on a frequent basis. Compared to interstellar dust, novae dust forms within a short time frame of 30 to 100 days after an outburst, allowing them to serve as perfect laboratories for understanding the formation and evolution of astrophysical dust. Dust formation in the hostile environment of novae ejecta has been an open question for many decades. Several attempts have been made to understand the physical and chemical conditions required to dust formation in novae ejecta and its relation with the observable parameters. However, due to the inherent complexity of the physical and chemical composition of novae ejecta and the multi-step process of dust grain formation, such attempts could only achieve partial success in explaining it. Thus, a more fundamental approach is required where multiple physical and chemical parameters of the dust forming novae ejecta are studied in detail, to estimate favorable conditions for the formation of dust. As a part of this work, we perform photoionization modeling of the dusty nova V1280 Scorpii (V1280 Sco) with the aim to study the changes in the physical and chemical parameters. We model the predust and postdust phase, optical and near-infrared spectra using the photoionization code CLOUDY, v.17.02, considering a two-component (low-density and high-density regions) model. It is found that a very high hydrogen density (∼10^13 –10^14 cm-3 ) is required for the proper generation of spectra. We also found that the dust condensation conditions are achieved at high ejecta density (∼3.16 × 10^8 cm -3 ) and low temperature (∼2000 K) in the outer region of the ejecta. |
