标题： SN 2014J的中间星云阶段：凝聚的开始作为复合的来源 显示英文标题

标题： The intermediate nebular phase of SN 2014J: onset of clumping as the source of recombination

摘要： 大约1岁时，大多数I型超新星的光谱由FeII和FeIII的强禁线发射线主导。 后来对邻近SN 2011fe的观测（约2年时）显示，电离度意外地转移到了FeI和FeII。 这里展示的非常邻近的Ia型超新星SN 2014J在中间阶段（1-1.5年）的光谱显示，FeIII发射逐渐减少，而FeI尚未强烈。 如果在约1.5年时，抛射物中的团块程度显著增加，就可以解释电离度的下降，至少在以Fe为主的区域是这样。 模型表明，团块在约一年后仍保持一致，表现得像碎片。 团块中的高密度与逐渐降低的加热率相结合，就会导致复合。 这些数据可能见证了从相对平滑的抛射物到典型的SN遗迹的非常团状形态的过渡阶段。 团块增加的起源可能是局部磁场的发展。 显示英文摘要

摘要： At the age of about 1 year, the spectra of most Type Ia supernovae are dominated by strong forbidden nebular emission lines of FeII and FeIII. Later observations (at about 2 years) of the nearby SN 2011fe showed an unexpected shift of ionization to FeI and FeII. Spectra of the very nearby SN Ia 2014J at an intermediate phase (1 - 1.5 years) that are presented here show a progressive decline of FeIII emission, while FeI is not yet strong. The decrease in ionization can be explained if the degree of clumping in the ejecta increases significantly at ~1.5 years, at least in the Fe-dominated zone. Models suggest that clumps remain coherent after about one year, behaving like shrapnel. The high density in the clumps, combined with the decreasing heating rate, would then cause recombination. These data may witness the phase of transition from relatively smooth ejecta to the very clumpy morphology that is typical of SN remnants. The origin of the increased clumping may be the development of local magnetic fields.