http://arxiv.org/abs/1708.05394
Nearby type Ia supernovae (SNe Ia), such as SN 2017cbv, are useful events to address the question of what the elusive progenitor systems of the explosions are. Hosseinzadeh et al. (2017a) suggested that the early blue excess of the lightcurve of SN 2017cbv could be due to the supernova ejecta interacting with a nondegenerate companion star. Different SN Ia progenitor models are predicted to have circumstellar (CS) environments in which strong outflows create low density cavities of different radii. Matter deposited at the edges of the cavities, should be at distances at which photoionisation due to early ultraviolet (UV) radiation of SNe Ia causes detectable changes to the observable Na I D and Ca II H&K absorption lines. To study narrow absorption lines, we obtained a time-series of high-resolution spectra of SN 2017cbv at phases between -14.8 and +83 days with respect to B-band maximum, covering the time at which photoionisation is predicted to occur. Both narrow Na I D and Ca II H&K are detected in all spectra, without there being any measurable changes between the epochs. Photoionisation models suggest that no detectable gas clouds were present between $\sim10^{15}$–$2\times10^{19}$ cm from SN 2017cbv. The limits exclude the presence of significant amounts of Na I and Ca II gas at distances some progenitor models suggest CS gas would be deposited.
R. Ferretti, R. Amanullah, M. Bulla, et. al.
Mon, 21 Aug 17
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Comments: N/A