超新星遗迹HB21中分子激波的红外研究：I.北方地区冲击H_2气的热掺混
Infrared Studies of Molecular Shocks in the Supernova Remnant HB21: I. Thermal Admixture of Shocked H_2 Gas in the North
摘要：
我们目前的近红外和中红外观测的冲击波云的相互作用区域在北部的超新星遗迹HB 21，与AKARI卫星上的红外相机（IRC）和宽红外相机（WIRC）在帕洛玛5米望远镜。IRC 7 μ m（S7）、11 μ m（S11）和15 μ m（L15）波段图像和WIRC H2 v = 1 -> 0 S（1）2.12 μ m图像显示了相似的激波-云相互作用特征。我们选择了三个有代表性的区域，并通过与几种冲击模型的H2线发射进行比较，分析了它们的IRC发射。IRC颜色可以用H2气体的热混合模型很好地解释，其无穷小的H2柱密度与温度T呈幂律关系，dN ~ T^-b dT，n（H2）~ 10^3 cm^-3，b ~ 3，N（H2 ;T > 100 K）~ 3 × 10^20 cm^-2。导出的b值可以用弓形激波图来理解，弓形激波图的形状是摆线（尖点）而不是抛物面。然而，这幅图提出了另一个问题，即弓形激波必须位于~0.01 pc尺度内，比理论上预期的要小。相反，我们拍摄了一张激波碰撞的星际介质图像，这可能在解释相似模型参数的同时避免尺寸尺度问题。观察到的H2 v = 1 -> 0 S（1）强度比幂律混合模型预测的强度大约17 - 33倍。这种过剩可能归因于热H2气体的额外组分，或者归因于与氢原子碰撞的效应，这在我们的幂律混合模型中被忽略了，这两者都会增加H2在v = 1能级的布居数。
英文摘要：
We present near- and mid-infrared observations on the shock-cloud interaction region in the northern part of the supernova remnant HB21, performed with the InfraRed Camera (IRC) aboard AKARI satellite and the Wide InfraRed Camera (WIRC) at the Palomar 5 m telescope. The IRC 7 um (S7), 11 um (S11), and 15 um (L15) band images and the WIRC H2 v = 1 -> 0 S(1) 2.12 um image show similar shock-cloud interaction features. We chose three representative regions, and analyzed their IRC emissions through comparison with H2 line emissions of several shock models. The IRC colors are well explained by the thermal admixture model of H2 gas--whose infinitesimal H2 column density has a power-law relation with the temperature T, dN ~ T^-b dT--with n(H2) ~ 10^3 cm^-3, b ~ 3, and N(H2 ;T > 100K) ~ 3x10^20 cm^-2. The derived b value may be understood by a bow shock picture, whose shape is cycloidal (cuspy) rather than paraboloidal. However, this picture raises another issue that the bow shocks must reside within ~0.01 pc size-scale, smaller than the theoretically expected. Instead, we conjectured a shocked clumpy interstellar medium picture, which may avoid the sizescale issue while explaining the similar model parameters. The observed H2 v = 1 -> 0 S(1) intensities are a factor of ~17 - 33 greater than the prediction from the power-law admixture model. This excess may be attributed to either an extra component of hot H2 gas or to the effects of collisions with hydrogen atoms, omitted in our power-law admixture model, both of which would increase the population in the v = 1 level of H2.
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