Dust Formation and Evolution in Envelope-Stripped Core-Collapse Supernovae
Takaya Nozawa1 (takaya.nozawa@ipmu.jp)
T. Kozasa2, N. Tominaga3, K. Maeda1, K. Nomoto1, M. Tanaka4, H. Umeda5
1IPMU (Institute for the Physics and Mathematics of the Universe), 2Hokkaido University, 3Konan University,
4NAOJ (National Astronomical Observatory of Japan), 5University of Tokyo〇 Abstract
Core-collapse supernovae (SNe) are considered to be one of the important sources of interstellar dust. However, it has not bee n explored how
the size and amount of dust formed in the ejecta depend on the types of SNe. We investigate the composition, average radius, and mass of dust
formed in the ejecta of envelope-stripped Type Ib and Type IIb SNe, and compare to those in Type II-P SNe with massive hydrogen envelopes.
We find that the total mass of dust formed in Type Ib/IIb SNe is 0.1-1.5 Msun and is in the range of the estimates of dust mass in Type II-P SNe.
However, the average radii of newly formed grains in Type Ib/IIb SNe are found to be less than 0.01 μm, which is about one or der of magnitude
smaller than those formed in Type II-P SNe. This implies that the size of dust formed in the ejecta is heavily affected by the outer envelope mass.
We also calculate the destruction of newly formed grains by the reverse shock in Type IIb SN remnants (SNRs) and find that these small grains
are almost completely destroyed in the shocked gas. Thus, we conclude that envelope-deficient SNe are unlikely to be major sources of dust.

〇 Dust Formation in Type Ib SN 2006jc (Nozawa et al. 2008)－ Calculation of dust formation in the SN ejecta (Nozawa et al. 2003)－ Model of SN 2006jc (Tominaga et al. 2008)
Mejecta = 4.9 Msun (MZAMS = 40 Msun, Z = 0.02), Ekin = 1052 erg s -1
－ Results of dust formation calculations
・ The average radii of dust formed are less than 0.01 μm (Figure 1),
because of a low gas density resulting from no envelope (Figure 2)
・ Total mass of dust that can form in the ejecta is 1.45 Msun

Fig. 2 – (a) Gas density and (b) velocity at 300 days after theexplosions within the He core for SN models of Type Ib (red),
Type IIb (green), and Type II-P (blue) with Meje = 17Msun,Menv = 13.2Msun, and Ekin = 1051erg (Umeda & Nomoto 2002).
The mass coordinate is normalized by the He core mass.

Fig. 1 – Average radii of dust grains formed in the ejecta
of Type Ib SN 2006jc as a function of enclosed mass.

〇 Dust Formation in Type IIb SNe (Nozawa et al. 2010)－ Models of Type IIb SN: SN 1993J-likeMejecta = 2.94 Msun (MZAMS = 18 Msun, Z=0.02), Ekin = 1051 erg s -1
－ Results of dust formation calculations
・ The average grain radii are below 0.01 μm (Figure 3), being muchsmaller than those (> 0.01 μm) formed in Type II-P SNe (Figure 4)
・ Total mass of dust formed in the ejecta is 0.167 Msun

Fig. 3 – Same as Figure 1, but for Type IIb SN model.

Fig. 4 – Same as Figure 1, but for Type II-P SN model.

〇 Evolution of Dust in Type IIb SNe (Nozawa et al. 2010)－ Calculation of dust evolution in SNRs (Nozawa et al. 2007)
・ treating the dynamics of dust grains and their destruction due tosputtering, along with the time evolution of shock propagation
・ Dust model: results from the above dust formation calculation－ Results of dust evolution calculations
・ Newly formed small grains are completely destroyed in the shockedgas for nH,0 ≥ 0.1 cm-3 before being injected into the ISM (Figure 5)➔ Envelope-poor SNe Ib/IIb are unlikely to be main suppliers ofinterstellar dust grains

Fig. 5 – Time evolution of the total mass of the newly formed dust within the Type IIb SNRs; (a) the uniform CSM with n H,0 =0.1 cm−3 (dotted), 1 cm−3 (solid), and 10 cm−3 (dashed), and (b) the stellar wind CSM with nH,1 = 30 cm−3 (dotted), 120 cm−3(solid), and 200 cm−3 (dashed), respectively, corresponding to the mass-loss rates of 2x10-5, 8x10-5, and 13x10-5 Msun yr-1.

〇 Comparison with Infrared Observations of Cassiopeia A SNR－ The observed infrared spectrum of Cas A SNR is well reproduced byour self-consistent model of dust formation and evolution (Figure 6)➔ warm dust of 0.008 Msun and cool dust of 0.072 Msun
－ AKARI and Herschel detect cool (35-40 K) dust towards Cas A (Figure 7)➔ estimated mass of cool dust is 0.03-0.075 Msun (Sibthorpe et al.
2010; Barlow et al. 2010) ➔ very consistent with our calculation!

Fig. 6 – Comparison between the infrared observations (bluedots, Hine et al. 2004) of Cas A SNR and the calculated dust
emission spectrum (red) in Type IIb SNR for nH,1 = 120 cm−3
at 330 yr. The green and black broken lines are, respectively,
the contributions from the shocked and unshocked dust.

〇 Summary－ In Type Ib/IIb SNe without massive envelopes, the radii of dust grains formed are small (< 0.01 μm)➔ Size of dust formed in the ejecta depends on the SN types through the mass of outer envelope－ Because of their small sizes, the newly formed grains are almost entirely destroyed inside the SNRs
➔ Envelope-stripped Type Ib/IIb SNe are not likely to be important sources of interstellar dust
－ Our dust formation and evolution models well reproduce the observed IR emission from Cas A SNR

Fig. 7 – Herschel image of Cas A at 70 µm subtracted by thenormalized Spitzer MIPS 24 µm image (Barlow et al. 2010).
The image is 7’ on a side. The inner and outer circles depict
the positions of the reverse and forward shocks, respectively(Gotthelf et al. 2001). This image manifests the emission
from cool dust that has not been swept by the reverse shock

References:
Barlow, M. J., et al. 2010, A&A, 518, L138
Gotthelf, E. V., et al. 2001, ApJ, 552, L39
Hines, D. C. et al., 2004, ApJS, 154, 290
Nozawa, T., et al. 2003, ApJ, 598, 785
Nozawa T., et al. 2007, ApJ, 666. 955
Nozawa, T., et al. 2008, ApJ, 684, 1313
Nozawa, T., et al. 2010, ApJ, 713, 356
Sibthorpe, B., et al. 2010, ApJ, 719, 1553
Tominaga, N., et al., 2008, ApJ, 687, 1208
Umeda & Nomoto 2002, ApJ, 565, 385