Study of the type IIP supernova 2008gz
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Transcript of Study of the type IIP supernova 2008gz
Study of the type IIP supernova 2008gz
Roy et al. 2011, MNRAS accepted
Supernovae: Catastrophic cosmic explosions
Energy released ~10^46 J
Responsible for chemical enrichment of galaxies
Trigger new star formation
SNe link to neutron stars, black holes, GRBs, …..
Progenitors & Process
1. White dwarf binary: thermonuclear
Accretion
Chandrasekhar limit
Explosion
Image: scienceblogs.com
Progenitors & Process
2. Massive stars: Core collapse
Star >10M_sun
Iron core - Chandrasekhar limit
Radiation pressure reduces
Gravitational core collapse
Remnant: neutron star, black hole
Image: smithsonianscience.com
Supernova family (spectra and light curve) Type I Type II
Ia Silicon lines
no Hydrogen Ib no Si but rich He
Ic no Si, poor/or no He
Ibc_pec (no H but unusual LC and spectra)
IIP, show plateau in the light curve
with Hydrogen IIL, linear decay of light curve
IIn, narrow emission lines
IIb, early time dominant H (like II)
But later similar to Ib
Image: astro.rug.nl SNe light curves
Supernovae family: (early spectra and light curve)
SN type I > 55%
SN type II ~ 41%
Core collapse SNe
Ib, Ic, Ibc_pec,
IIL, IIP, IIb, IIn
Smith, N. et al. 2010
Type IIP SNe show variation in their luminosity, velocity and Ni production.
Supernova 2008gz
Host: Spiral galaxy NGC 3672
Explosion date (UT): 5.83 Nov 2008
RΑ (J2000): 11h 25m 3s
DEC (J2000): -09º 47' 51''
Observations:
BVRI data
1m, ST ARIES, India
2m, IGO IUCAA, India
3.6m, NTT ESO, Chile
Spectra
2m, IUCAA
3.5m, TNG
3.6m, NTT
6m, SAO Russia
Light curve in BVRI magnitudes
+87d to +275d since explosion
SN detected very close to end
of plateau phase
Time of inflection 115± 5 days
Bolometric light curve
Nebular phase governed by radioactive decay of Ni to Co to Fe
=> tail luminosity is proportional to Ni synthesized.
(Arnett 1980, 1996)
Derived tail luminosity
= 1.51± 0.29 * 10^41 erg/s
Comparison of absolute V mag to other IIP SNe
Unusual V dropping ~1.5mag
during plateau to nebular phase
SN 2008gz spectra (late plateau to deep nebular )
Late plateau
Nebular
Late nebular
Velocity profile of different elements
Photospheric velocity is a good indicator of explosion energy
(Dessart et al. 2010)
=>SN 2008gz has explosion energy 2.3*10^51erg similar to SN2004et
Summary Photometric and spectral nature of this event is similar to
normal type IIP SNe 2004et and 1999em. The plateau phase lasted about 115±5 days.
Photospheric velocity ~ 4000 km/s at similar epoch comparable to SN 2004et.
Explosion energy 2-3 * 10^51 erg/s. SN 2008gz exhibits rarely observed drop of 1.5 mag in V,
within 30 days from plateau to nebular phase. Synthesized Ni during the explosion 0.05± 0.01 M_sun.