Transcript About_Me_files/5min09ipx

A panchromatic view of the restless
SN2009ip reveals the explosive ejection of
a massive stellar envelope
The complete story…
Distance of 24 Mpc
In the outskirts of NGC7259
Sub-solar metallicity
environment 0.4<Z<0.9 Zsun
Discovery
Explosion1
Outburst
Explosion2
Outburst
Now
Sep 2012
Aug 2012
Oct 2011
May 2011
Sep 2010
Jul 2010
Aug 2009
Outburst
UV-Optical-NIR photometry
SN2009ip eruptions plus
2012 double explosion
Eruptions
2012
“Precursor bump”
Major explosion
Why is SN2009ip so interesting?
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
SN2009ip vs. a sample of SNe IIn and the peculiar
explosion 1961V
Our observational campaign:
VLA
CARMA
13-filter
photometry
+ spectra
UVOT
&
HST
XMM
XRT
BAT
Fermi-LAT
…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
The general picture:
40 days
Low-energy explosion:
Erad~3d49 erg NOT
powered by Nickel!
Mshell~0.1 Msun
August 2012
“shell ejection”
A second explosions
happens
September 2012
The shock breaks out through the
dense thick shell ejected by the
first explosion
X-rays:
they peak around the
same time of the
optical emission
Radio:
Delayed peak due
to free-free
absorption
…however:
Lx / Lopt < 10-4
As expected for a
shock break out
through a dense
medium
Lbol/1d4
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=tpk-4.5d
The NIR excess is not due to line
emission
GeV photons and neutrinos from shock
break-out
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. FermiLAT upper-limits are shown with black circles.
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 (ECR).
NIR emitting
material
ejected during
the previous
years outbursts
R>4d15 cm
R~5d14 cm
E~1d50 erg
Mej~0.5 Msun
DENSE and compact SHELL
M~0.1 Msun
(ejected by the 2012
precursor)
The general picture is that of a massive star that repeatedly ejects massive shells of
material on a time scale of years and less
What triggers the sudden shell ejection?
This is not clear. However, two observational facts are crucial to our understanding:
Presence of a
dominant timescale common to
eruption
episodes and the
major explosion,
shared by
completely
independent
events
40 days
Extreme similarity to SN2010mc, which implies:
-- Causal connection between precursor and main explosion
-- “SIMPLE” mechanism
-- Important channel for mass loss
Note: this NOT a
claim for periodicity
Take-away message
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.
Ref in the literature:
Smith 2010; Foley 2011; Fraser 2013; Levesque 2013; Mauerhan 2013;
Ofek 2013; Pastorello 2013; Prieto 2012; Smith 2013; Soker 2013