Formation of Dust in Supernovae
and Its Ejection into the ISM
Takaya Nozawa(IPMU, Univ. of Tokyo)
Collaborators;
T. Kozasa (Hokkaido Univ.), N. Tominaga (Konan Univ.),
K. Maeda (IPMU), H. Umeda (Univ. of Tokyo),
K. Nomoto (IPMU/Univ. of Tokyo)

1. Introduction

1-1. Background
CCSNe are main sources of interstellar dust?
－ formation of dust in the ejecta of SNe－ destruction of dust in the shocked gas of SNRs
・ Observations of dust-forming SNe➔ no information on composition and size of dust
except for SN 2006jc (Sakon+2009) and SN 2004et (Kotak+2009)➔ Mdust <10-3 Msun
・ Theoretical studies➔ Mform = 0.1-1 Msun for SNe II
various dust species with 0.001-1 μm(Todini & Ferrara 2001; Nozawa et al. 2003)➔ Msurv = 0.01-0.8 Msun for nH,0=0.1-10 cm-3
(Bianchi & Schneider 2007; Nozawa et al. 2007)

1-2. Aim of our study
・ Comparison of models with IR observations of SNRs
－ erosion by sputtering and collisional heating➔ properties of dust and density structure in CSM

What size and how much amount of dust are
injected from CCSNe into the ISM?
・ Dust formation and evolution in SN with no envelope－ 30-40% of CCSNe explode as SNe Ib/c and SN IIb(Prieto et al. 2009; Smartt et al. 2008; Boissier & Prantzos 2009)

How do formation and destruction processesof dust depend on the type of CCSNe?

1-3. Outline
・ Formation of dust in the ejecta of Type IIb SN➔ composition, size, and mass of newly formed dust

・ Destruction of dust in the hot gas of the SNR➔ What fraction of dust grains in the SN ejecta cansurvive and is injected into the ISM?

・ Thermal emission from shock-heated dust
➔ comparison with IR observations of Cas A SNR➔ constraint to gas density in the ambient medium

1-4. Cassiopeia A SNR○ Cas A SNR－ age: ~330 yr (Thorstensen et al. 2001)－ distance: d=3.4 kpc (Reed et al. 1995)－ shock radius
forward shock : ~150” (~2.5 pc)
reverse shock : ~100” (~1.7 pc)
dM/dt ~ 2x10-5 (vw/10 km/s) Msun/yr(Chevalier & Oishi 2003)－ oxygen-rich SNR
dense O-rich fast-moving knots (O, Ar, S, Si, Fe …)
thermal emission from ejecta-dust➔ Mdust = 0.02-0.054 Msun (Rho et al. 2008)－ SN type : Type IIb (Krause et al. 2008)

2. Formation of dust in Type IIb SN

2-1. Dust formation calculation○ Type IIb SN model(SN1993J-like model)－ Meje = 2.94 Msun
MH-env = 0.08 Msun
Mstar = 18 Msun

－ E51 = 1－ M(56Ni) = 0.07 Msun

○ Dust formation calculation－ non-steady nucleation andgrain growth theory(Nozawa et al. 2003)－ onion-like composition

2-2. Composition and mass of dust formed
Mass of dust formed

Total mass of dust formed :0.167 Msun in SN IIb
0.1-1 Msun in SN II-P

condensation time・ different species of dust cancondense in different layers

・ condensation time:300-700 days

2-3. Radius of dust formed in the ejecta
average radius

SN IIbSN II-P (Mstar=20 Msun)
Grain radius➔ > 0.01 μm for SN IIP➔ < 0.01 μm for SN IIb
Dust grains formed in Hdeficient SNe are small

3. Evolution of dust in Type IIb SNR

3-1. Calculation of dust evolution in SNRs
○ Model of calculations(Nozawa et al. 2006, 2007)

・ejecta model－ hydrodynamic model fordust formation calculation
・CSM gas density－ nH = 1.0 and 10.0 cm-3－ nH(r) ∝ M / (4πr2 vw) g/cm-3(M = 2x10-5 Msun/yr)

・treating dust as a test particle－ erosion by sputtering－ deceleration by gas drag－ collsional heating➔ stochastic heating3-2. Evolution of dust in Type IIb SNR
n=1.0 /cc

n=10.0 /cc

3-3. Time evolution of dust mass
n=1.0 /cc

n=10.0 /cc

Mdust ~ 10-4 Msun at 105 yr

Mdust = 0 Msun at 105 yr

Newly formed dust grains in the ejecta are completely
destroyed in the shocked gas within the SNR
Core-collapse SNe with the thin outer envelope cannot
be main sources of dust

4. Thermal emission of dust in SNRs

4-1. Thermal emission from dust in the SNR・ thermal radiation from dust ← temperature of dust
・ equilibrium temperature of dust in SNR is determined bycollisional heating with gas and radiative cooling
H (a, n, Tg)= Λ(a, Qabs, Td) ➔ thermal emission
・ small-sized dust grains (＜0.01 μm) ➔ stochastic heating

4-2. Time evolution of IR thermal emission (1)Data: Hines et al. (2004)
red: with SH
green: without SH4-3. Time evolution of IR thermal emission (2)Data: Hines et al. (2004)
red: with SH
green: without SH4-4. Time evolution of IR SEDs for Cas A SNR
240 yr

340 yr

440 yr

540 yr

Data: Hines et al. (2004)
red: with SH
green: without SH4-5. Dependence of IR SED on ambient density
ρ x 1.6

ρ x 3.3

Md = 0.06 Msun

ρx5

ρ x 10

Data: Hines et al. (2004)
red: with SH
green: without SH

4-6. Contribution from circumstellar dust
・ dust species
C and Mg2SiO4・ dust size distributionf(a) ∝ a^-3.5
amin = 0.001 μm
amax = 0.5 μm
・ MC : Msil = 3 : 7CMg2SiO4

red: ejecta dust
blue: CSM dust

Summary1) The radius of dust formed in the ejecta of Type IIb SN isquite small (＜0.01 μm) because of low ejecta density
2) Small dust grains formed in Type IIb SN cannot survive
destruction in the shocked gas within the SNR3) Model of dust destruction and heating in Type IIb SNR
to reproduce the observed SED of Cas A isMd,eje = 0.06 Msun, Md,ism = 0.03-0.07 Msun
dM/dt = 6.6x10-5 Msun/yr4) IR SED reflects the destruction and stochastic heating➔ properties (size and composition) of dust
➔ density structure of circumstellar medium