SN 1986J VLBI. III. The Central Component Becomes Dominant
SN 1986J VLBI. III. The Central Component Becomes Dominant
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SN 1986J VLBI。
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
N. Bartel
中科院分区：
文献类型：
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作者：
M. Bietenholz;N. Bartel
我们提出了一个新的5 GHz的全球甚长基线干涉（VLBI）图像的超新星1986J，在2014年观察到的t = 31.6年后爆炸，并将其与以前的图像进行比较，以显示超新星的演变。我们的新图像具有100 μ J的动态范围和5.9 μJy beam−1的背景均方根噪声水平。没有明显的线性偏振，图像峰值<3%偏振。最新的图像是由一个紧凑的中心组成部分，其通量密度现在可以与扩展的超新星壳相媲美。该中心分量以的FWHM边缘分辨，对应于10 Mpc距离的半径。利用2002年至2014年的VLBI观测，我们测量了类星体3C 66A的中心分量和壳层中NE方向的热点的自行。中心分量的不确定度为12 μas yr−1，相当于570 km s−1。我们的观测结果表明，中心分量位于SN 1986J的物理中心附近。壳层热点向东北方向的平均速度为2810 ± 750 km s−1，这与它参与壳层的同系膨胀相一致。壳层发射以非自相似的方式演化，最亮的发射在结构内部向内移动，只有在外缘和假定的前向激波附近看到相对微弱的发射。爆炸的动画是可用的。
We present a new 5 GHz global very-long-baseline interferometry (VLBI) image of supernova 1986J, observed in 2014 at t = 31.6 yr after the explosion, and compare it to previous images to show the evolution of the supernova. Our new image has a dynamic range of ∼100 and a background rms noise level of 5.9 μJy beam−1. There is no significant linear polarization, with the image peak <3% polarized. The latest image is dominated by a compact central component, whose flux density is now comparable to that of the extended supernova shell. This central component is marginally resolved with an FWHM of , corresponding to a radius of for a distance of 10 Mpc. Using VLBI observations between 2002 and 2014, we measured the proper motions of both the central component and a hot spot to the NE in the shell relative to the quasar 3C 66A. The central component is stationary to within the uncertainty of 12 μas yr−1, corresponding to 570 km s−1. Our observations argue that the central component is located near the physical center of SN 1986J. The shell hot spot had a mean velocity of 2810 ± 750 km s−1 to the NE, which is consistent with its taking part in the homologous expansion of the shell seen earlier. The shell emission is evolving in a non-self-similar fashion, with the brightest emission shifting inward within the structure and with only relatively faint emission seen near the outer edge and the presumed forward shock. An animation of the explosion is available.