studio fotometrico e spettroscopico di sn 1994z, rara supernova iip dal plateau brillante

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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studio fotometrico e spettroscopico di sn 1994z, rara supernova iip dal plateau brillante

Documents

zampieri et

h typeii

similar evolution

ni mass correlation

standard luminosity

photometric data reduction

obervational data light

high luminosity iip