Photoionization modeling of the dusty nova V1280 Scorpii
  We perform photoionization modeling of the dusty nova V1280 Scorpii (V1280
Sco) with an aim to study the changes in the physical and chemical parameters.
We model pre and post dust phase, optical and near-Infrared (NIR), spectra
using the photoionization code \textsc{cloudy}, v.17.02, considering a
two-component (low density and high density region) model. From the best-fit
model, we find that the temperature and luminosity of the central ionizing
source in the pre-dust phase are in the range 1.32 - 1.50 $\times 10^4$ K and
2.95 - 3.16 $\times 10^{36}$ ergs$^{-1}$, respectively, which increase to 1.58
- 1.62 $\times 10^4$ K and 3.23 - 3.31 $\times 10^{36}$ ergs$^{-1}$,
respectively, in the post-dust phase. It is found that a very high hydrogen
density ($\sim 10^{13} - 10^{14}$ cm$^{-3}$) is required for the generation of
spectra properly. Dust condensation conditions are achieved at high ejecta
density ($\sim 3.16 \times 10^{8}$cm$^{-3}$) and low temperature ($\sim$2000 K)
in the outer region of the ejecta. It is found that a mixture of small (0.005 -
0.25$\mu$m) amorphous carbon dust grains and large (0.03 - 3.0$\mu$m)
astrophysical silicate dust grains iis present n the ejecta in the post-dust
phase. Our model yields very high elemental abundance values as C/H = 13.5 -
20, N/H = 250, O/H = 27 - 35, by number, relative to solar in the ejecta,
during the pre-dust phase, which decrease in the post-dust phase.
