Infrared and X-Ray Evidence for Circumstellar Grain Destruction by the Blast Wave of Supernova 1987A
Infrared and X-Ray Evidence for Circumstellar Grain Destruction by the Blast Wave of Supernova 1987A
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1987A 超新星爆炸波破坏恒星周围颗粒的红外和 X 射线证据
DOI：
10.1086/529038
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
C. Woodward
中科院分区：
文献类型：
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作者：
E. Dwek;R. Arendt;P. Bouchet;D. Burrows;P. Challis;I. J. Danziger;J. D. De Buizer;R. Gehrz;R. Kirshner;R. McCray;Sangwook Park;E. Polomski;C. Woodward
对超新星遗迹1987A的多波长观测表明，随着爆炸产生的冲击波扩展到恒星周围的赤道环，它的形态和光度在x射线、光学、红外（IR）和无线电波长上发生了迅速的变化。观测到的红外辐射来自于在质量流出中形成的尘埃颗粒与激波气体的软x射线发射等离子体成分的相互作用。斯皮策红外光谱仪在爆炸后第6190天拍摄的5-30 μm的光谱显示，辐射来自于~1.1 × 10−6 M☉的硅酸盐颗粒，辐射温度为~180−15+20 K。第7137天的后续观测表明，红外通量增加了2倍，同时保持了几乎相同的光谱形状。观测到的红外- x射线通量比（IRX）与具有标准大麦哲伦星云尘埃丰度的尘埃等离子体一致。IRX在第6190天至7137天之间减少了约2倍，首次在动态时间尺度上直接观测到超新星爆炸波膨胀过程中尘埃的持续破坏。与观测到的尘埃温度、软x射线发射组分的电离时间尺度和IRX的演化相一致的详细模型表明，辐射的硅酸盐颗粒浸没在3.5 × 106 K、密度为（0.3-1）× 104 cm−3的等离子体中，其尺寸分布被限制在0.023 ~ 0.22 μm的狭窄半径范围内。较小的颗粒可能已经被超新星最初的紫外线闪光蒸发掉了。
Multiwavelength observations of supernova remnant 1987A show that its morphology and luminosity are rapidly changing at X-ray, optical, infrared (IR), and radio wavelengths as the blast wave from the explosion expands into the circumstellar equatorial ring, produced by mass loss from the progenitor star. The observed IR radiation arises from the interaction of dust grains that formed in mass outflow with the soft X-ray-emitting plasma component of the shocked gas. Spitzer Infrared Spectrograph spectra at 5-30 μm taken on day 6190 since the explosion show that the emission arises from ~1.1 × 10−6 M☉ of silicate grains radiating at a temperature of ~180−15+20 K. Subsequent observations on day 7137 show that the IR flux had increased by a factor of 2 while maintaining an almost identical spectral shape. The observed IR-to-X-ray flux ratio (IRX) is consistent with that of a dusty plasma with standard Large Magellanic Cloud dust abundances. IRX has decreased by a factor of ~2 between days 6190 and 7137, providing the first direct observation of the ongoing destruction of dust in an expanding supernova blast wave on dynamic timescales. Detailed models consistent with the observed dust temperature, the ionization timescale of the soft X-ray emission component, and the evolution of IRX suggest that the radiating silicate grains are immersed in a 3.5 × 106 K plasma with a density of (0.3–1) × 104 cm−3 and have a size distribution that is confined to a narrow range of radii between 0.023 and 0.22 μm. Smaller grains may have been evaporated by the initial UV flash from the supernova.