arXiv 1012.20352010-12-22astro-ph.SR

II-P型超新星2004 dj喷出物中的尘埃形成

Dust formation in the ejecta of the Type II-P supernova 2004dj

T. Szalai, J. Vinkó, Z. Balog, A. Gáspár, M. Block, L. L. Kiss

备注：: 15 pages, 11 figures, 8 tables; accepted for publication in A&A; new version after minor corrections and language edition
DOI：: 10.1051/0004-6361/201015624

摘要：

核心坍缩超新星（CC SNe），特别是II型高原超新星，被认为是宇宙尘埃产生的重要贡献者。SN 2004 dj是自1987年以来最接近和最明亮的SN之一，为研究尘埃形成过程提供了一个很好的机会。为了找到新形成的尘埃的迹象，我们分析了斯皮策太空望远镜所有可用的中红外（MIR）档案数据。我们重新整理和分析了IRAC，MIPS和IRS仪器在爆炸后+98和+1381天之间获得的数据，生成了每个时期的光变曲线和光谱。观测到的光谱能量分布与分析和数值模型，后者使用辐射传输代码MOCASSIN。我们还使用哈勃太空望远镜在+425天获得的成像偏振数据。我们提出了令人信服的证据尘埃形成的喷出物SN 2004 dj从MIR光变曲线和光谱。在3.6和24 μ m之间的所有波段中检测到显著的MIR过量通量。在光学上，在2-sigma水平上也检测到~0.8%的偏振，这超过了该方向上的星际偏振。我们的分析表明，SN 2004 dj周围新形成的尘埃可以模拟为含有无定形碳颗粒的近球形壳，在+267和+1246天之间从~700 K冷却到~400 K。在10 μ m以上发现了持续的过量通量，这是由冷（~115 K）尘埃成分解释的。如果这些寒冷的尘埃是星周起源的，那么它很可能在前向和反向冲击波之间的一个寒冷而致密的壳层中凝结。先前存在的星周尘埃的可能性较小，但不能排除。尘埃质量的上限为~ 8 × 10 ^{-4} M_sun，这与以前发表的其他产生尘埃的SNe的值相似。

英文摘要：

Core-collapse supernovae (CC SNe), especially Type II-Plateau ones, are thought to be important contributors to cosmic dust production. SN 2004dj, one of the closest and brightest SN since 1987A, offered a good opportunity to examine dust formation processes. To find signs of newly formed dust, we analyze all available mid-infrared (MIR) archival data from the Spitzer Space Telescope. We re-reduce and analyze data from IRAC, MIPS and IRS instruments obtained between +98 and +1381 days after explosion, generating light curves and spectra for each epoch. Observed spectral energy distributions are fitted with both analytic and numerical models, using the radiative-transfer code MOCASSIN for the latter ones. We also use imaging polarimetric data obtained at +425 days by the Hubble Space Telescope. We present convincing evidence of dust formation in the ejecta of SN 2004dj from MIR light curves and spectra. Significant MIR excess flux is detected in all bands between 3.6 and 24 um. In the optical, a ~0.8% polarization is also detected at a 2-sigma level, which exceeds the interstellar polarization in that direction. Our analysis shows that the freshly-formed dust around SN 2004dj can be modeled assuming a nearly spherical shell containing amorphous carbon grains, cooling from ~700 K to ~400 K between +267 and +1246 days. Persistent excess flux has been found above 10 um, which is explained by a cold (~115 K) dust component. If this cold dust is of circumstellar origin, it is likely to be condensed in a cool, dense shell between the forward and reverse shocks. Pre-existing circumstellar dust is less likely, but cannot be ruled out. An upper limit of ~8x10^{-4} M_sun was derived for the dust mass, which is similar to previously published values for other dust-producing SNe.

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