Common continuum polarization properties: a possible link between proto-planetary nebulae and Type Ia Supernova progenitors

Abstract

Abstract The lines of sight to highly reddened SNe Ia show peculiar continuum polarization curves, growing towards blue wavelengths and peaking at $\lambda _{\text{max}} \lesssim 0.4 \,\mu \mathrm{m}$, like no other sightline to any normal Galactic star. We examined continuum polarization measurements of a sample of asymptotic giant branch (AGB) and post-AGB stars from the literature, finding that some proto-planetary nebulae (PPNe) have polarization curves similar to those observed along SN Ia sightlines. These polarization curves are produced by scattering on circumstellar dust. We discuss the similarity and the possibility that at least some SNe Ia might explode during the post-AGB phase of their binary companion. Furthermore, we speculate that the peculiar SN Ia polarization curves might provide observational support to the core-degenerate progenitor model.