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Studio fotometrico e spettroscopico di SN 1994Z, rara supernova IIP dal plateau brillante Dipartimento di Astronomia, Università degli Studi di Padova.

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Presentation on theme: "Studio fotometrico e spettroscopico di SN 1994Z, rara supernova IIP dal plateau brillante Dipartimento di Astronomia, Università degli Studi di Padova."— Presentation transcript:

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

2 Geremeas, 22 maggio Modern classification Turatto, 2003

3 Geremeas, 22 maggio 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…

4 Geremeas, 22 maggio 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 4 th, by P. Philips at CTIO) Spectra analysis => typical features of a II-P SN 2-3 weeks after explosion (on October 4 th, by S. Benetti and G. Hasinger on ESO 2.2m telescope spectra) SN 1994Z NGC 87 RA 00h,21m,16.6s DEC -48d,37m,49s H vel 3546 TARGET OF ESO-KEY PROJECTS

5 Geremeas, 22 maggio Dataset ~ 500 days photometric coverage ~ 380 days spectroscopic coverage

6 Geremeas, 22 maggio Basic Estimates for Photometry Milky Way Reddening: A B,MW =0.084 (Schlegel et al. 1998) A B,pg =0 No Host Galaxy reddening (no NaID, Turatto et al. 2003) Distance through Hubbles law v infall =3371km/s (LEDA), H 0 =72±4 km/s/Mpc (Freedman, 2001): d= Mpc = Explosion Date through comparison with similar objects: D expl =13 September 1994

7 Geremeas, 22 maggio 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 Geremeas, 22 maggio V =1.07mag/100d Plateau luminosity not perfectly constant for V, R, I bands

9 Geremeas, 22 maggio For comparison: Absolute UBVRI light curves U B V R I

10 Geremeas, 22 maggio Absolute magnitudes M max,B V,plat. ~ , R,plat. ~ , I,plat. ~ 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

11 Geremeas, 22 maggio SN 2004et Pastorello (private communication) Colour… …And bolometric light curve M( 56 Ni)~0.07 M (as for SN 1987A!)

12 Geremeas, 22 maggio Spectroscopy 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… Photosferic phase H H HeI H [FeII] ScII CaII] FeII NaID H FeIIScII FeII T cont ~13000K T cont ~6200K v ph ~9000km/s v ph ~2300km/s Nebular phase H CaII] [OI] CaII-IR

13 Geremeas, 22 maggio Comparisons: SN 1992H H Velocity …therefore: Similar kinematics and structure of the nebulae

14 Geremeas, 22 maggio OI line luminosity CaII line luminosity H line luminosity But… Less massive progenitor for SN 1994Z! Different Envelope masses, less massive for 94Z Different line luminosities M Henv ~ 10M

15 Geremeas, 22 maggio 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 envelope envelope mass ejected 56 Ni mass velocity of the env. at the outer shell explosion energy luminosity at recombination Output parameters:

16 Geremeas, 22 maggio Best fit Progenitor mass: ~9.5M

17 Geremeas, 22 maggio Correlation among II-P SNe physical parameters See Hamuy et al (2003) Zampieri et al (2003) Zampieri (2006)

18 Geremeas, 22 maggio 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 56 Ni 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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20 Geremeas, 22 maggio 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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