Supernovae
Oscar Straniero INAF – Oss. Astr. di Collurania (TE)
SNe Classification
Core collapse of massive stars
Thermonuclear explosion
I b (strong He)
I c (weak He)
SNe
II p
Type II
II L
No H
H
Type I
I a (strong Si)
based on spectra and light curve morphology
Standard Candles Bright Homogeneous No evolutionary effects
Supernovae Ia
Light Curve
L
time
56Ni 56Co 56 Fe
Thermonuclear Explosionof a CO WDM~MChandrasekhar
L MNi
~ 1.4 M
Observed Relations Riess et al. , 1997
Brighter Slower Decline
Dimmer Faster Decline
Calibrated locally
Phillips et al. 1996, 1999
<> = 0.17 mag
Maximum Brightness - Decline Relation
…… bombs often fail. Similarly, most models for astrophysical bombs (Sne Ia) often fail.
The conceptually simplest model for a thermonuclear supernova is just an analog of a runaway chemical reaction that become explosive : a conventional bomb.
…… Further, astrophysical bombs must occur naturally and at the correct rate: there must be a convincing astronomical context.
log
log
P
5/3
4/3
M1
M2
Non-degenerate
Non-relativistic
relativistic
collapse
The virial theorem
5.1
3
1
0
2
0
M
Md
M
R
r
Mq
VPR
GMq
r
dMMG
rr
Rrr
g
3
2
3
442 MRMP
457.15.0
83.5 2
Che
eCh
MYif
YM
Massive stars and
core collapse
18.145.0 Che MY
• e-+p n+e (10 MeV)
• 56Fe+ 13+4n (124 MeV)
Limongi, Straniero & Chieffi, 2001
Evolutionary track of low mass stars
0.6 CO
0.55 He 0.2 CO
0.1 He
0.5 He
0.6 CO
WD
MS
RGBHB
AGB
PNM=1 M
=10 Gyr
Remnant: CO WD 0.6 M
Prada Moroni & Straniero 2002
Stellar evolution
M<0.8 M
0.8<M/M<8
8<M/M<11
11<M/M<100
M>100 M
GyrMyr 0.5<Mf /M<1.1 CO WD
Myr Mf
=1.2-1.3 M ONeMg WD
1-10 Myr Mf =1.2-2.5 M Fe (Ye0.45) collapse NS or BH1Myr O (pair jnstability) (Ye=0.5) may or may not explode
Astrophysical Explosive Devices
Gravitational collapse
Induced Core collapse (nuclear runaway fails)
Pair instability, core collapse & O explosion (core collapse fails)
C-deflagration
C or He detonation
C-delayed detonation
Thermonuclear SNe
RGWD
WD WD
Nucleosynthesisin Thermonuclear
SNe
He-detonation
C-delayed detonation
C-deflagration
SNe Ia Light Curves: mass
and metallicity effects
Domínguez, Hoflich, Straniero 2001
Most of the accreted material is lost during the H-pulse:
too long time
H accreting WDs
RG MS
Merging scenario:Double degenerate systems: CO+CO a) GWR loss
b) secondary tidal disruption
c) accretion 10-5 Myr-1
Too fast accretion
(M=810-6 M yr-1)
Double Degenerate CO WDs
(M=10-8 M yr-1)
Single Degenerate.
Massive WDs: the lifting effect of
rotation
H
HeCO
Dominguez, Straniero, Isern & Tornambe’ 1996
Double DegenerateAngular momentum deposition & GWR
c) accretion 10-5 Myr-1 (expansion)
d) “critical” accretion (contraction)
e) tri-axial configuration and energy loss via GWR
f) balance between ang. mom. deposition and energy loss (steady accretion)
g) Viscous dissipation and explosion
d
c ef g
---- disk ---- WD
Piersanti, Gagliardi, Iben & Tornambe’ 2003
Massive stars
e,e+
Convective regions
At the onset of the core collapse
18.145.0 Che MY
• e-+p n+e (10 MeV)
• 56Fe+ 13+4n (124 MeV)
Pressure contributions
COLLAPSE, BOUNCE & STALL
+0.2 ms
-0.5 ms +2.0 ms
1012 g/cm3
3x1014 g/cm3
Photo-dissociation & neutronization
e-+p n+e
Neutrino Energy Deposition &
Convection: the way trough a successful
explosion
neutrino energy =1053 erg
kinetic + energy =1051 erg
SN IIp: Light Curves