Powering the second 2012 outburst of SN 2009ip by repeating binary interaction

We propose that the major 2012 outburst of the supernova impostor SN 2009ip was powered by an extended and repeated interaction between the luminous blue variable (LBV) and a more compact companion. Motivated by the recent analysis of Margutti et al. (2013) of ejected clumps and shells, we consider two scenarios. In both scenarios, the major 2012b outburst with total (radiated + kinetic) energy of ~5 × 10⁴⁹ erg was powered by accretion of ~2- 5M_⊙ on to the companion during a periastron passage (the first passage) of the binary system approximately 20 d before the observed maximum of the light curve. In the first scenario, the surviving companion scenario, the companion was not destructed and still exists in the system after the outburst. It ejected partial shells (or collimated outflows or clumps) for two consecutive periastron passages after the major one. The orbital period was reduced from ~38 to ~25 d as a result of the mass transfer process that took place during the first periastron passage. In the second scenario, the merger scenario, some partial shells/clumps were also ejected in a second periastron passage that took place ~20 d after the first one. After this secondperiastron passage, the companion dived too deep into the LBV envelope to launch more outflows and merged with the LBV.