Powering the Second 2012 Outburst of SN 2009ip by Repeating Binary Interaction

TL;DR

This paper suggests that the 2012 outburst of SN 2009ip was caused by repeated binary interactions, involving accretion and possible merger, which powered the energetic outburst and altered the binary orbit.

Contribution

It introduces two scenarios explaining the 2012 outburst through binary interaction and accretion, offering a new interpretation of SN 2009ip's behavior.

Findings

The outburst was powered by accretion of 2-5 solar masses onto a companion.

The orbital period decreased from ~38 days to ~25 days after the outburst.

Two scenarios: surviving companion and merger, explain different post-outburst behaviors.

Abstract

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 x 10^{49} erg was powered by accretion of 2-5 solar masses onto the companion during a periastron passage (the first passage) of the binary system approximately 20 days 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 days to ~25 days 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 ejected also in a second periastron passage that took place ~20 days after the first one. After this second periastron passage the companion dived too deep into the LBV envelope to launch more outflows, and merged with the LBV.