Accelerating very fast gas in the supernova impostor SN 2009ip with jets from a stellar companion

Using hydrodynamic numerical simulations we show that high-velocity ejecta with v ∼ 10⁴ km s^-1 in the outbursts of the supernova impostor SN 2009ip and similar luminous blue variable (LBV) stars can be explained by the interaction of fast jets, having v_jet ∼ 2000-3000 km s^-1, with a circumbinary shell (extended envelope). The density profile in the shell is very steep such that the shock wave, that is excited by the jets' interaction with the shell, accelerates to high velocities as it propagates outward. The amount of very fast ejecta is small, but sufficient to account for some absorption lines. Such an extended envelope can be formed from the binary interaction and/or the unstable phase of the LBV primary star. The jets themselves are launched by the more compact secondary star near periastron passages.