A panchromatic view of the restless SN2009ip reveals the explosive
  ejection of a massive star envelope
  The 2012 explosion of SN2009ip raises questions about our understanding of
the late stages of massive star evolution. Here we present a comprehensive
study of SN2009ip during its remarkable re-brightening(s). High-cadence
photometric and spectroscopic observations from the GeV to the radio band
obtained from a variety of ground-based and space facilities (including the
VLA, Swift, Fermi, HST and XMM) constrain SN2009ip to be a low energy (E~ 10^50
erg for an ejecta mass ~ 0.5 Msun) and likely asymmetric explosion in a complex
medium shaped by multiple eruptions of the restless progenitor star. Most of
the energy is radiated as a result of the shock breaking out through a dense
shell of material located at 5x10^14 cm with M~0.1 Msun, ejected by the
precursor outburst ~40 days before the major explosion. We interpret the NIR
excess of emission as signature of dust vaporization of material located
further out (R>4x 10^15 cm), the origin of which has to be connected with
documented mass loss episodes in the previous years. Our modeling predicts
bright neutrino emission associated with the shock break-out if the cosmic ray
energy is comparable to the radiated energy. We connect this phenomenology with
the explosive ejection of the outer layers of the massive progenitor star, that
later interacted with material deposited in the surroundings by previous
eruptions. Future observations will reveal if the luminous blue variable (LBV)
progenitor star survived. Irrespective of whether the explosion was terminal,
SN2009ip brought to light the existence of new channels for sustained episodic
mass-loss, the physical origin of which has yet to be identified.
