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Studio fotometrico e spettroscopico di SN 1994Z, rara supernova IIP dal plateau brillante

Dipartimento di Astronomia, Universit à degli Studi di Padova INAF – Osservatorio Astronomico di Padova. Studio fotometrico e spettroscopico di SN 1994Z, rara supernova IIP dal plateau brillante. Irene Agnoletto. Geremeas (CA), 20-26 maggio 2007. Modern classification. Turatto, 2003.

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Studio fotometrico e spettroscopico di SN 1994Z, rara supernova IIP dal plateau brillante

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  1. Dipartimento di Astronomia, Università degli Studi di Padova INAF – Osservatorio Astronomico di Padova Studio fotometrico e spettroscopico di SN 1994Z, rara supernova IIP dal plateau brillante Irene Agnoletto Geremeas (CA), 20-26 maggio 2007

  2. Modern classification Turatto, 2003

  3. Core collapsesupernovae: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…

  4. Presentation NGC 87 SN 1994Z • 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 SN2-3 weeks after explosion (on October 4th, by S. Benetti and G. Hasinger on ESO 2.2m telescope spectra) TARGET OF ESO-KEY PROJECTS 1990-1996 H vel 3546 RA 00h,21m,16.6s DEC -48d,37m,49s

  5. Dataset ~ 500 days photometric coverage ~ 380 days spectroscopic coverage

  6. Basic Estimates for Photometry • Milky Way Reddening:AB,MW=0.084(Schlegel et al. 1998) • AB,pg=0No 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

  7. 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

  8. Plateau luminosity not perfectly constant for V, R, I bands V=1.07mag/100d

  9. U B I R V Absolute UBVRI light curves For comparison:

  10. Absolute magnitudes 94Z 96W 92H V band 96W 92H 87A 94Z 69L V band • 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!!

  11. M(56Ni)~0.07 M  (as for SN 1987A!) SN 2004et Pastorello (private communication) Colour… …And bolometric light curve

  12. Spectroscopy Photosferic phase FeII H Nebular phase CaII] FeII ScII NaID ScII H FeII [FeII] Tcont~6200K vph~2300km/s CaII-IR H H Tcont~13000K HeI H vph~9000km/s CaII] [OI] • Standard IRAF reduction procedure • Wavelength calibration through HeNe or HeAr lamps spectra • SN flux calibration through instrument sensitivity functions RESULT: THE WHOLE SPECTROSCOPIC EVOLUTION IS…

  13. Comparisons: SN 1992H H Velocity …therefore: Similar kinematics and structure of the nebulae

  14. But… OI line luminosity 6300-6364 CaII line luminosity 7291-7332 Different line luminosities H line luminosity Different Envelope masses, less massive for 94Z Less massive progenitor for SN 1994Z! MHenv~10M 

  15. Modelling • initial radius of the envelope • envelope mass • ejected 56Ni mass • velocity of the env. at the outer shell • explosion energy • luminosity at recombination Output parameters: • Comparison between obervational data(light curves, evolution of the line velocity and continuum temperature) andnumerical simulations (Zampieri et al. 2003) • Automatic data fitting

  16. Best fit Progenitor mass:~9.5M 

  17. Correlation among II-P SNe physical parameters See Hamuy et al (2003) Zampieri et al (2003) Zampieri (2006)

  18. 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);

  19. 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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