Sec$on 8.
Mechanism of core-collapse supernovae
8.1 Core-collapse
8.2 Mechanism of core-collapse supernovae

Goals of this lecture• Standard proper$es of stars• Stellar structure and proper$es• Stellar evolu$on• Origin of the elements in the Universe• Nucleosynthesis in stars and supernovae• Explosion mechanism of supernovae• Topics in $me-domain astronomy• Radia$on from explosive phenomena• Mul$-messenger astronomy

Collapse(< 1 sec)

Neutron star
orBlack holeSupernova!

What triggers the collapse of the star??

Sec$on 8.
Mechanism of core-collapse supernovae
8.1 Core-collapse
8.2 Mechanism of core-collapse supernovae

Sec$on 8.
Mechanism of core-collapse supernovae
8.1 Core-collapse
8.2 Mechanism of core-collapse supernovae

Results of simula$ons (1D)SUMIYOSHI ET AL.

Vol. 629

Radius (km)Sumiyoshi+05

ShockFailure
1 sec
Time (s)(thick lines) and LS (thin lines) as a function of time after bounce. The evolution at early (left) and late (right)Why do stars ﬁnally explode?
Why is it diﬃcult to reproduce explosions?

ν(1)(2)Neutrino trapping

Core-collapseνeFeνν ννFe coreννν	

ShockSN neutrinoν"νν ννν ννν ννν ννν(3)Core bounce
図 1.4

ν

(4)

(5)

Supernova

Neutron star(C) 原子核から読み解く超新星爆発の世界

重力崩壊型超新星の爆発メカニズムの概要．重い星の中心部にある鉄住吉光介さん著 (Kosuke Sumiyoshi)
コアの重力崩壊から始まり，密度・温度が高まる中で発生したニュー(C) A. Burrows

Suwa et al. 2011

Suwa et al.
Suwa et al. 2011

1000

RadiusRadius (km)
[km]

07a).
pears
ssive
er ofoups.
ave a09).
modmotoatinga exironpro2006)
m 2D
sport[VShock
1D simula$on100100.4 sec
050

100 150 200 250 300 350 400 450Time（msec）
Timeafter bounce [ms]E ~ 1050 erg (smaller than observa$ons by 1 order of magnitude)
Fig. 1. Time evolution of Models M13-1D and M13-2D, v
Oneof the bybiggest
in moderninastrophysics
sualizedmassmysteryshell trajectories
thin gray and orang

SN 1987A(in Large Magellanic cloud, 50 kpc)

Neutrino detec$on
From SN 1987A
Kamiokande(C) ICRR

nsion between KAMIOKANDE and IMB data

Enu ~ 1053 erg!!
=> Founda$on of neutrinodriven mechanism* Observed energy(an$ electron neutrino) x 6

FIG. 2. Contours of constant likelihood which correspond toJegerlehner et al. 1996
3%, 90%, and 95.4% confidence regions, and best-fit values forAssignment 4Kamiokande detected 11 neutrino events from SN 1987A.
By this fact, es$mate total neutrino energythat SN 1987A released- You can assume the same numbers for all the ﬂavors (6 ﬂavors).
- protons in water are main reactor (Cross sec$on σ ~ 10-41 cm2 )- Eﬀec$ve volume of Kamiokande 2 kton
- Distance to the LMC is 50 kpc+⌫¯e + p ! e + n

レポート課題 4
カミオカンデで11イベントのニュートリノが観測された。
このことから、SN 1987Aがニュートリノとして放出した総エネルギーを概算せよ* すべてのフレーバーのニュートリノが同数放出されたと仮定して良い* 主な反応は水分子中の陽子 (反応断面積σ ~ 10-41 cm2 )* カミオカンデの有効体積 2 kton
* 大マゼラン雲までの距離 50 kpc+⌫¯e + p ! e + nSummary: Core-collapse supernovae• Core-collapse• Triggered by electron capture and photo dissociaAon• Explosion mechanism=> Bounce => Shock stalled• Core-collapse=> neutrino heaAng• Neutrino detecAon from SN 1987A• Detailed mechanism is not yet solved• Explosive nucleosynthesis• 56Ni => heaAng source of supernova

Let’s understand these ques$ons
Knowing = Understanding
with the word of physics• Why do some stars explode?
• Why don’t normal star explode?
• Why do stars show L ~ M ?
• Why do stars evolve?
• Why does the des$ny of stars depend on the mass?
• Why does stellar core collapses?
• Why is the energy of supernova so huge?
•…
4Thermodynamics

Electromagne$sm

Classical
mechanics

Sta$s$cal
mechanics

Astrophysics
Hydrodynamics

Rela$vityQuantum
mechanics
Nuclear physics

Appendix

Timescales of core-collapse supernovae

Core-collapse~0.1 sec

BounceShock revival~0.1-1 sec

Shock breakoutt(breakout) = R(RSG)/v(SN)~ 1014/109 ~ 105 sec~ 1 dayBreakout~1 day (~105 sec)

R(RSG) ~ 1000 Rsun
~ 1014 cmv(SN) ~ 10,000 km/s
(109 cm/s)

Mass fraction log10(x)u. Rev. Astron. Astrophys. 2013.51:457-509. Downloaded from ww
by Kokuritsu-Tenmondai Libr. - National Observatory of Japan onBefore

c0–656Ni

54Fe

116O

24He

34

1H24Mg228Si–440Ca56Mr (M )Nomoto+13

5Mass fraction log10(x)1Hd56Ni

04He16O

1H24Mg2

Central remnant

Aver

28Si

–440Ca54Fe

6–6

123456Mr (M )Nomoto+13