# SN 2009ip at late times - an interacting transient at +2 years

Fraser, M, Kotak, R, Pastorello, A, Jerkstrand, A, Smartt, SJ, Chen, T-W, Childress, M, Gilmore, G, Inserra, C, Kankare, E, Margheim, S, Mattila, S, Valenti, S, Ashall, C, Benetti, S, Botticella, MT, Bauer, FE, Campbell, H, Elias-Rosa, N, Fleury, M , Gal-Yam, A, Hachinger, S, Howell, DA, Guillou, LL, Léget, P-F, Morales-Garoffolo, A, Polshaw, J, Spiro, S, Sullivan, M, Taubenberger, S, Turatto, M, Walker, ES, Young, DR and Zhang, B (2015) SN 2009ip at late times - an interacting transient at +2 years. Monthly Notices of the Royal Astronomical Society, 453 (4). pp. 3886-3905. ISSN 0035-8711

We present photometric and spectroscopic observations of the interacting transient SN 2009ip taken during the 2013 and 2014 observing seasons. We characterise the photometric evolution as a steady and smooth decline in all bands, with a decline rate that is slower than expected for a solely $^{56}$Co-powered supernova at late phases. No further outbursts or eruptions were seen over a two year period from 2012 December until 2014 December. SN 2009ip remains brighter than its historic minimum from pre-discovery images. Spectroscopically, SN 2009ip continues to be dominated by strong, narrow ($\lesssim$2000 km~s$^{-1}$) emission lines of H, He, Ca, and Fe. While we make tenuous detections of [Fe~{\sc ii}] $\lambda$7155 and [O~{\sc i}] $\lambda\lambda$6300,6364 lines at the end of 2013 June and the start of 2013 October respectively, we see no strong broad nebular emission lines that could point to a core-collapse origin. In general, the lines appear relatively symmetric, with the exception of our final spectrum in 2014 May, when we observe the appearance of a redshifted shoulder of emission at +550 km~s$^{-1}$. The lines are not blue-shifted, and we see no significant near- or mid-infrared excess. From the spectroscopic and photometric evolution of SN 2009ip until 820 days after the start of the 2012a event, we still see no conclusive evidence for core-collapse, although whether any such signs could be masked by ongoing interaction is unclear.