In order to understand the contribution of core-collapse supernovae to the dust budget of the early universe , it is important to understand not only the mass of dust that can form in core-collapse supernovae but also the location and rate of dust formation .
SN 2005ip is of particular interest since dust has been inferred to have formed in both the ejecta and the post-shock region behind the radiative reverse shock .
We have collated eight optical archival spectra that span the lifetime of SN 2005ip and we additionally present a new X-shooter optical–near-IR spectrum of SN 2005ip at 4075 d post-discovery .
Using the Monte Carlo line transfer code damocles , we have modelled the blueshifted broad and intermediate width H \alpha , H \beta and He i lines from 48 d to 4075 d post-discovery using an ejecta dust model .
We find that dust in the ejecta can account for the asymmetries observed in the broad and intermediate width H \alpha , H \beta and He i line profiles at all epochs and that it is not necessary to invoke post-shock dust formation to explain the blueshifting observed in the intermediate width post-shock lines .
Using a Bayesian approach , we have determined the evolution of the ejecta dust mass in SN 2005ip over 10 years presuming an ejecta dust model , with an increasing dust mass from \sim 10 ^ { -8 } M _ { \odot } at 48 d to a current dust mass of \sim 0.1 M _ { \odot } .