SN 1987 A残留物的五年中红外演化：冲击波与尘埃赤道环的相遇
Five Years of Mid-Infrared Evolution of the Remnant of SN 1987A: The Encounter Between the Blast Wave and the Dusty Equatorial Ring
摘要：
我们已经使用斯皮策卫星监测SN 1987 A的中红外演化超过5年的时间跨度之间的6000和8000天，因为爆炸。超新星（SN）已经演化为超新星遗迹（SNR），其辐射输出主要是由SN爆炸波与预先存在的赤道环（ER）的相互作用。中红外光谱主要由约180 K的硅酸盐尘埃发射，由温度和密度分别为约5x10^6 K和3x10^4 cm-3的热X射线发射气体碰撞加热。在第7554天，辐射尘埃的质量约为1.2 × 10 ^（-6）Msun，与红外通量呈线性关系。红外线与软X射线的通量比大致恒定，为2.5。因此，气体-颗粒碰撞控制了受冲击气体的冷却。这一比例的恒定性表明，在这一时期几乎没有发生过谷物加工或气体冷却。尘埃光谱的形状在观测过程中保持不变，而总通量随着时间的t^（0.87）而增加，t是爆炸波和ER之间第一次相遇的时间。这些观察结果与爆炸波从自由膨胀到Sedov阶段的过渡是一致的，因为它传播到ER的主体。
英文摘要：
We have used the Spitzer satellite to monitor the mid-IR evolution of SN 1987A over a 5 year period spanning the epochs between days 6000 and 8000 since the explosion. The supernova (SN) has evolved into a supernova remnant (SNR) and its radiative output is dominated by the interaction of the SN blast wave with the pre-existing equatorial ring (ER). The mid-IR spectrum is dominated by emission from ~180 K silicate dust, collisionally-heated by the hot X-ray emitting gas with a temperature and density of ~5x10^6 K and 3x10^4 cm-3, respectively. The mass of the radiating dust is ~1.2x10^(-6) Msun on day 7554, and scales linearly with IR flux. The infrared to soft-X-ray flux ratio is roughly constant with a value of 2.5. Gas-grain collisions therefore dominate the cooling of the shocked gas. The constancy of of this ratio suggests that very little grain processing or gas cooling have occurred throughout this epoch. The shape of the dust spectrum remained unchanged during the observations while the total flux increased with a time dependence of t^(0.87), t being the time since the first encounter between the blast wave and the ER. These observations are consistent with the transitioning of the blast wave from free expansion to a Sedov phase as it propagates into the main body of the ER.
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