FORMATION OF DUST IN THE EJECTA OF TYPE Ia SUPERNOVAE
FORMATION OF DUST IN THE EJECTA OF TYPE Ia SUPERNOVAE
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DOI：
10.1088/0004-637x/736/1/45
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发表时间：
2011-05
期刊：
影响因子：
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通讯作者：
T. Nozawa;K. Maeda;T. Kozasa;Masaomi Tanaka;K. Nomoto;H. Umeda
中科院分区：
文献类型：
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作者：
T. Nozawa;K. Maeda;T. Kozasa;Masaomi Tanaka;K. Nomoto;H. Umeda
采用碳爆燃W7模型研究了Ia型超新星(SNE Ia)喷出物中尘埃颗粒的形成。在尘埃形成的计算中，我们应用成核和颗粒生长理论，考虑了CO和SiO分子形成的两种极端情况：完全形成和NO形成。计算结果表明，对于α的粘着概率j=1，C、硅酸盐、硅和FeS颗粒可在∼爆炸后100-300d的早期凝聚，而Fe和碳化硅颗粒基本不能形成。由于无H包络的SneIa中气体密度较低，新形成的颗粒平均半径一般在0.01μm以下，远小于II-P型Sne中的平均半径。这支持了我们之前的结论，即在质量较小的近地天体中，喷出物中形成的尘埃半径较小。当−j=0.1-1时，总粉尘质量从3×10☉4M☉到0.2Mα，取决于是否形成CO和SiO分子。我们还估算了新形成的尘埃的光学厚度和热发射，并与SNE Ia的相关观测结果进行了比较。我们发现，必须抑制SneIa中C颗粒的形成，才能与观测约束一致。这意味着高能光子和电子严重降低了C颗粒的形成效率，或者说SNE Ia最外层的C-O层几乎完全燃烧。最后，我们计算了SN残留物中的尘埃破坏，发现在SNE Ia喷射物中形成的尘埃颗粒在被注入星际介质之前，在激波气体中几乎被完全摧毁。这表明SNE Ia不太可能是星际尘埃的主要来源。
We investigate the formation of dust grains in the ejecta of Type Ia supernovae (SNe Ia), adopting the carbon-deflagration W7 model. In the calculations of dust formation, we apply the nucleation and grain growth theory and consider the two extreme cases of the formation of CO and SiO molecules: complete formation and no formation. The results of the calculations show that for the sticking probability of αj = 1, C, silicate, Si, and FeS grains can condense at early times of ∼100–300 days after the explosion, whereas Fe and SiC grains cannot form substantially. Due to the low gas density in SNe Ia with no H-envelope, the average radii of the newly formed grains are generally below 0.01 μm, being much smaller than those in Type II-P SNe. This supports our previous conclusion that the radius of dust formed in the ejecta is smaller in SNe with less massive envelopes. The total dust mass ranges from 3 × 10−4 M☉ to 0.2 M☉ for αj = 0.1–1, depending on whether or not CO and SiO molecules are formed. We also estimate the optical depths and thermal emission by the newly formed dust and compare them to the relevant observations of SNe Ia. We find that the formation of C grains in SNe Ia must be suppressed to be consistent with observational constraints. This implies that energetic photons and electrons heavily depress the formation efficiency of C grains or that the outermost C–O layer of SNe Ia is almost fully burned. Finally, we calculate dust destruction in the SN remnants and find that dust grains formed in the ejecta of SNe Ia are almost completely destroyed in the shocked gas before being injected into the interstellar medium. This indicates that SNe Ia are unlikely to be the major sources of interstellar dust.