A panchromatic view of the restless SN2009ip reveals the explosive ejection of a massive stellar envelope

Distance of 24 Mpc In the outskirts of NGC7259 Sub-solar metallicity environment 0.4<Z<0.9 Zsun Discovery Aug 2009 Outburst Jul 2010 Outburst Sep 2010 Outburst May 2011Oct 2011 Explosion2 Explosion1 Aug 2012Sep kpc Now Supernova ImpostorSupernova ? The complete story…

Eruptions 2012 SN2009ip eruptions plus 2012 double explosion UV-Optical-NIR photometry “Precursor bump” Major explosion

We know the story of eruptions of the progenitor in the previous years The explosion has a luminous PRECURSOR Detection of the PROGENITOR star in pre-explosion images (Smith+10, Foley+11): the progenitor is a massive star with M>60 Msun Why is SN2009ip so interesting? SN2009ip vs. a sample of SNe IIn and the peculiar explosion 1961V

VLA CARMA 13-filter photometry + spectra UVOT & HST XMM XRT BAT Fermi-LAT Our observational campaign: …no wavelength is left behind… The extensive monitoring is critical to: (i) constrain Erad, the temperature and radius of the emission; (ii) constrain the role of different emission processes that dominate at different wavelengths. Understand the global properties of the explosion

Low-energy explosion: E rad ~3d49 erg NOT powered by Nickel! 40 days August 2012 “shell ejection” September 2012 The shock breaks out through the dense thick shell ejected by the first explosion A second explosions happens The general picture: Mshell~0.1 Msun

L x / L opt < Lbol/1d4 X-rays: they peak around the same time of the optical emission …however: As expected for a shock break out through a dense medium Radio: Delayed peak due to free-free absorption SN2009ip is a weak radio and X-ray emitter!

The metamorphosis in the optical: BUT…

No sign of freshly synthesized material, yet See e.g. [OI]

Low-res UVOT spectral campaign HST Oct 29 Nov 06

Super SED around the time of the optical peak NIR excess of emission

NIR campaign: NIR excess: t=t pk -4.5d The NIR excess is not due to line emission

GeV photons and neutrinos from shock break-out Predicted muon and anti-muon neutrino fluence from SN 2009ip using the observables and explosion parameters according to the model by Murase et al. (2011). For this event, the atmospheric neutrino background is more severe since SN 2009ip occurred in the southern hemisphere. For better localized explosions, this plot shows how limits on the neutrino emission can be used to constrain the energy in cosmic rays (E CR ). The collision of the ejecta with massive shells is expected to accelerate cosmic rays (CRs) and generate GeV gamma- rays (Murase et al. 2011; Katz et al. 2011) with fluence that depends both on the explosion and on the environment parameters. We use the parameters inferred from the modeling of the optical-UV emission with shock break out, to predict the expected GeV fluence. Fermi- LAT upper-limits are shown with black circles.

DENSE and compact SHELL M~0.1 Msun (ejected by the 2012 precursor) R~5d14 cm R>4d15 cm NIR emitting material ejected during the previous years outbursts E~1d50 erg Mej~0.5 Msun The general picture is that of a massive star that repeatedly ejects massive shells of material on a time scale of years and less

Presence of a dominant time- scale common to eruption episodes and the major explosion, shared by completely independent events  40 days -- Causal connection between precursor and main explosion -- “SIMPLE” mechanism -- Important channel for mass loss What triggers the sudden shell ejection? This is not clear. However, two observational facts are crucial to our understanding: Extreme similarity to SN2010mc, which implies: Note: this NOT a claim for periodicity

Evolved massive stars have a much less boring life than expected: they suffer repetitive shell ejection on short time scales, whose physical origin is not understood, questioning our current understanding of massive star evolution. SN2009ip (and 10mc) might have just shown us a new channel for impulsive and sustained mass loss. Smith 2010; Foley 2011; Fraser 2013; Levesque 2013; Mauerhan 2013; Ofek 2013; Pastorello 2013; Prieto 2012; Smith 2013; Soker 2013 Ref in the literature: Take-away message