Post on 15-Jan-2016
description
Studio fotometrico e spettroscopico di SN 1994Z,
rara supernova IIP dal plateau brillante
Dipartimento di Astronomia, Università degli Studi di PadovaINAF – Osservatorio Astronomico di Padova
Irene Agnoletto
Geremeas (CA), 20-26 maggio 2007
Geremeas, 22 maggio 2007
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Modern classification
Turatto, 2003
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Core collapse supernovae: basic properties
originate from the energy liberated by the gravitational collapse of the nucleus of massive stars (> 8 M )
show H (typeII), He (except for type Ic), Ca, O, Mg, Fe
from small to huge radio to X-ray emissions
leave collapsed remnant (NS or BH)
emit neutrinos and gravitational waves
occur only in late type galaxies and are associated with star forming regions
are very heterogeneous: large spread in luminosity, ejected Ni masses, light curves evolution…
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Presentation
Discovered on October, 2.51 UT in the irregular galaxy NGC 87 (Wassilief, IAUC n. 6087)
First mag. estimation: V ~ 16, (B-V)~0.1 (on
October 4th, by P. Philips at CTIO) Spectra analysis => typical features of a II-P SN 2-3 weeks after
explosion (on October 4th, by S. Benetti and G. Hasinger on ESO 2.2m telescope spectra)
SN 1994Z
NGC 87
RA 00h,21m,16.6sDEC -48d,37m,49s
H vel 3546
TARGET OF
ESO-KEY PROJECTS 1990-1996
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Dataset
~ 500 days photometric coverage
~ 380 days spectroscopic coverage
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Basic Estimates for Photometry
Milky Way Reddening: AB,MW=0.084 (Schlegel et al. 1998)
AB,pg=0 No Host Galaxy reddening (no NaID, Turatto et al. 2003)
Distance through Hubble’s law vinfall=3371km/s (LEDA), H0=72±4 km/s/Mpc (Freedman, 2001): d= 46.81 Mpc = 33.35
Explosion Date through comparison with similar objects: Dexpl=13 September 1994
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Photometric data reduction and results
Both aperture and PSF photometry with SNOoPY (Cappellaro & Patat)
Calibration through Landolt (1992) standard stars
Calibration of SN in not photometric nights through local sequence stars
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V=1.07mag/100d
Plateau luminosity not perfectly constant for V, R, I bands
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For comparison:
Absolute UBVRI light curves
U
B
VR
I
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Absolute magnitudes
Mmax,B ≤ -17.29 <M>V,plat.~ -17.05,
<M>R,plat.~ -17.32,
<M>I,plat.~ -17.62
Similar evolution to SN 1996W and SN 1992H (photosferic phase) but …
standard luminosity tail!!
92H
94Z
96W
V band
87A
V band
94Z
96W
92H
69L
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SN 2004et
Pastorello (private communication)
Colour…
…And bolometric light curve
M(56Ni)~0.07 M (as for SN 1987A!)
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Spectroscopy
Standard IRAF reduction procedure Wavelength calibration through HeNe or
HeAr lamps spectra SN flux calibration through instrument
sensitivity functionsRESULT: THE WHOLE SPECTROSCOPIC
EVOLUTION IS…
Photosferic phase
H
HHeI
H
[FeII]ScII CaII]
FeIINaIDH
FeII ScIIFeII
Tcont~13000K
Tcont~6200K
vph~9000km/s
vph~2300km/s
Nebular phase
H
CaII][OI]
CaII-IR
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Comparisons: SN 1992H
H Velocity
…therefore:
Similar kinematics and structure of
the nebulae
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OI line luminosity6300-6364
CaII line luminosity7291-7332
H line luminosity
But…
Less massive progenitor for SN 1994Z!
Different Envelope masses, less massive for 94Z
Different line luminosities
MHenv ~10M
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Modelling Comparison between
obervational data (light curves, evolution of the line velocity and continuum
temperature) and numerical simulations (Zampieri et al. 2003)
Automatic data fitting initial radius of the envelopeenvelope massejected 56Ni massvelocity of the env. at the outer shellexplosion energyluminosity at recombination
Output parameters:
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Best fit
Progenitor mass: ~9.5M
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Correlation among II-P SNe physical parameters
See Hamuy et al (2003) Zampieri et al (2003) Zampieri (2006)
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Conclusions: SN 1994Z belongs to the poor populated class of bright
IIP SNe
Similar to SN 1996W and SN 1992H in brightness and kinematics at first stages, but with smaller amount of 56Ni ejected (maybe because of fallback??)
No evidence of Luminosity-Ni mass correlation!! (Hamuy, 2003)
High luminosity IIP supernovae can be associated with low mass progenitors
Standard physical parameters except for velocity
progenitor mass of ~9.5M => consistent with the recent progenitor identifications!! (see Li et al., 2006 for SN 2005cs, Li et al., 2005b for SN 2004et, Hendry & Smartt 2006 for SN 2004A);
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Observational data physical parameters (progenitor mass
and radius, energetics and velocity of the explosion etc.) nature, evolution
Bright II-P supernovae are rare More information are important, more
data are necessary!
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