Fig. 3: Time evolution of the different radii.
From: Newly formed dust within the circumstellar environment of SN Ia-CSM 2018evt
The BB photospheric radius \({R}_{{{{\rm{BB}}}}}^{{{{\rm{Opt}}}}}\) and the BB dust radius \({R}_{{{{\rm{BB}}}}}^{{{{\rm{MIR}}}}}\) are derived by fitting a BB spectrum to the optical-to-NIR luminosity and the MIR flux excesses, respectively. The latter is displayed in Fig. 4, and the associated temperature of the newly formed dust can be seen from the inset of Fig. 6. The horizontal grey-dashed line indicates the inner radius of the inner shell of the CSM (2.2 × 1016 cm) in the double-shell model. The inset presents the temporal evolution of the FWHM width of the broad Hα line. Two blue line segments present linear fits of the data before and after day +310, respectively. The shock radius Rs was derived by equation (1) in ‘BB fit and dust sublimation’ by assuming that the shock velocity was 10,000 km s−1 before the first observation at day ~+120 and approximated by the FWHM width of the broad Hα afterward. The error bars shown represent 1σ uncertainties of FWHM.
