High Angular Resolution ALMA Images of Dust and Molecules in the SN 1987A Ejecta
High Angular Resolution ALMA Images of Dust and Molecules in the SN 1987A Ejecta
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DOI：
10.3847/1538-4357/ab4b46
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发表时间：
2019-10
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通讯作者：
P. Cigan;M. Matsuura;H. Gomez;R. Indebetouw;F. Abellán;M. Gabler;A. Richards;D. Alp;T. Davis;H. Janka;J. Spyromilio;M. Barlow;D. Burrows;E. Dwek;C. Fransson;B. Gaensler;J. Larsson;P. Bouchet;P. Lundqvist;J. Marcaide;C. Ng;Sangwook Park;P. Roche;J. V. van Loon;J. Wheeler;G. Zanardo
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作者：
P. Cigan;M. Matsuura;H. Gomez;R. Indebetouw;F. Abellán;M. Gabler;A. Richards;D. Alp;T. Davis;H. Janka;J. Spyromilio;M. Barlow;D. Burrows;E. Dwek;C. Fransson;B. Gaensler;J. Larsson;P. Bouchet;P. Lundqvist;J. Marcaide;C. Ng;Sangwook Park;P. Roche;J. V. van Loon;J. Wheeler;G. Zanardo
我们给出了SN 1987 A系统的高角分辨率（1080 mas）阿尔马连续谱图像，以及CO J = 2 1，J = 6 5，SiO J = 5 4到J = 7 6的图像，这些图像清晰地分辨出了喷出物（尘埃连续谱和分子）和环（同步辐射连续谱）成分。喷出物中的尘埃是不对称的，呈块状，总的来说，尘埃填充了Hα图像中的空间空隙，用重元素的物质填充了该区域。尘埃团一般填充的空间，CO J = 6 5是微弱的，初步表明，这些尘埃团和CO的位置和化学联系。在这些地区，含碳尘埃颗粒可能已经形成后，CO的解离。尘埃颗粒会通过辐射冷却，随后的碰撞颗粒与气体也会冷却气体，抑制CO J = 6 - 5强度。数据显示，尘埃峰空间上与分子孔在以前的阿尔马CO J = 2 - 1和SiO J = 5 - 4图像。结合CO和SiO谱线，尘埃峰值表明尘埃和气体可能处于比周围物质更高的温度下，尽管不能完全排除更高的密度。其中一种可能性是，一个紧凑的来源提供额外的热量在该位置。与远红外-毫米光谱能量分布的拟合给出了18-23 K的喷出物尘埃温度。对于碳或硅酸盐颗粒，我们将喷出物尘埃质量修正为Mdust = 0.2-0.4，或者对于颗粒种类的混合物，最大值<0.7，使用预测的核合成产额作为上限。
We present high angular resolution (∼80 mas) ALMA continuum images of the SN 1987A system, together with CO J = 2 1, J = 6 5, and SiO J = 5 4 to J = 7 6 images, which clearly resolve the ejecta (dust continuum and molecules) and ring (synchrotron continuum) components. Dust in the ejecta is asymmetric and clumpy, and overall the dust fills the spatial void seen in Hα images, filling that region with material from heavier elements. The dust clumps generally fill the space where CO J = 6 5 is fainter, tentatively indicating that these dust clumps and CO are locationally and chemically linked. In these regions, carbonaceous dust grains might have formed after dissociation of CO. The dust grains would have cooled by radiation, and subsequent collisions of grains with gas would also cool the gas, suppressing the CO J = 6 5 intensity. The data show a dust peak spatially coincident with the molecular hole seen in previous ALMA CO J = 2 1 and SiO J = 5 4 images. That dust peak, combined with CO and SiO line spectra, suggests that the dust and gas could be at higher temperatures than the surrounding material, though higher density cannot be totally excluded. One of the possibilities is that a compact source provides additional heat at that location. Fits to the far-infrared–millimeter spectral energy distribution give ejecta dust temperatures of 18–23 K. We revise the ejecta dust mass to Mdust = 0.2–0.4 for carbon or silicate grains, or a maximum of <0.7 for a mixture of grain species, using the predicted nucleosynthesis yields as an upper limit.