Late Spectral Evolution of SN 1987A. I. Temperature and Ionization
Late Spectral Evolution of SN 1987A. I. Temperature and Ionization
复制标题
SN 1987A 的晚期光谱演化。
DOI：
10.1086/305409
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
C. Fransson
中科院分区：
文献类型：
--
作者：
C. Kozma;C. Fransson
SN 1987 A的温度和电离是在星云相200至2000天之间随时间变化的。我们包括所有重要的元素，以及超新星的主要成分区。能量输入由56 Co、57 Co和44 Ti的放射性衰变提供。由此产生的伽马射线和正电子的热化通过求解Spencer-Fano方程来计算。电离和个别水平的人口计算的时间依赖性。绝热冷却包括在能量方程中。电荷转移对于确定电离是重要的，并且包括在可用和估计的速率中。完整的，多级原子用于观测上重要的离子。作为输入模型的计算，我们使用的爆炸模型SN 1987 A计算的Woosley等人。和Nomoto等人。本文中最重要的结果涉及的温度和电离的各个丰度区的演变。富含金属的核心在600-1000天内经历了一次热不稳定性，通常被称为IR灾难。富氢区在500-800天后随温度变化，而在氦区，绝热冷却和线冷却在约1000天后同样重要。在氢区和氦区，复合的冻结是重要的。随着红外突变的发生，大部分辐射从光学和近红外谱线向中红外和远红外谱线移动，红外突变后的冷却主要是由于远红外谱线和绝热膨胀。在粉尘形成的区域，粉尘冷却可能很重要。我们发现，尘埃凝结温度发生在富氧区晚于~500天，最有利的尘埃凝结区是铁芯。引入的不确定性（在某些情况下）未知的电荷转移率进行了讨论。特别是对于低丰度的离子，差异可能很大。
The temperature and ionization of SN 1987A are modeled time-dependently in its nebular phase between 200 and 2000 days. We include all important elements, as well as the primary composition zones in the supernova. The energy input is provided by radioactive decay of 56Co,57Co, and 44Ti. The thermalization of the resulting gamma-rays and positrons is calculated by solving the Spencer-Fano equation. Both the ionization and the individual level populations are calculated time-dependently. Adiabatic cooling is included in the energy equation. Charge transfer is important for determining the ionization, and is included with available and estimated rates. Full, multilevel atoms are used for the observationally important ions. As input models for the calculations we use explosion models for SN 1987A calculated by Woosley et al. and Nomoto et al. The most important result in this paper concerns the evolution of the temperature and ionization of the various abundance zones. The metal-rich core undergoes a thermal instability, often referred to as the IR catastrophe, at 600-1000 days. The hydrogen-rich zones evolve adiabatically after 500-800 days, while in the helium region both adiabatic cooling and line cooling are of equal importance after ~1000 days. Freezeout of the recombination is important in the hydrogen and helium zones. Concomitant with the IR catastrophe, the bulk of the emission shifts from optical and near-IR lines to the mid- and far-IR. After the IR catastrophe, the cooling is mainly due to far-IR lines and adiabatic expansion. Dust cooling is likely to be important in the zones where dust forms. We find that the dust condensation temperatures occur later than ~500 days in the oxygen-rich zones, and that the most favorable zone for dust condensation is the iron core. The uncertainties introduced by the (in some cases) unknown charge transfer rates are discussed. Especially for ions with low abundances, differences can be substantial.