2015ApJ...803L..26M

We constrain the explosion and circumstellar properties at the 2012b event of SN 2009ip based on its recently reported late-phase bolometric light curve. The explosion energy and ejected mass at the 2012b event are estimated as 0.01 M_☉ and 2x10⁴⁹ erg, respectively. The circumstellar medium is assumed to have two components: an inner shell and an outer wind. The inner shell, which is likely created at the 2012a event, has a mass of 0.2 M_☉. The outer wind is created by the wind mass loss before the 2012a mass ejection, and the progenitor is estimated to have had a mass-loss rate of about 0.1 M_☉/yr with a wind velocity of 550 km/s before the 2012a event. The estimated explosion energy and ejected mass indicate that the 2012b event is not caused by a regular SN.