A Closer Look at the Fluctuations in Brightness of SN 2009ip During Its Late 2012 Eruption

Abstract

The supernova impostor SN 2009ip has re-brightened several times since its initial discovery in August 2009. During its last outburst in late September 2012 it reached a peak brightness of m$_v$ $\sim$ 13.5 (M$_v$ brighter than -18) causing some to speculate that it had undergone a terminal core-collapse supernova. Relatively high-cadence multi-wavelength photometry of the post-peak decline revealed bumps in brightness infrequently observed in other Type IIn supernovae. These bumps occurred synchronously in all UV and optical bands with amplitudes of 0.1 -- 0.4 mag at intervals of 10 -- 30 days. Episodic continuum brightening and dimming in the UV and optical with these characteristics is not easilly explained within the context of models that have been proposed for the late September 2012 outburst of SN 2009ip. We also present evidence that the post peak fluctuations in brightness occur at regular intervals and raise more questions about their origin.