SN 1986J VLBI: The Evolution and Deceleration of the Complex Source and a Search for a Pulsar Nebula
SN 1986J VLBI: The Evolution and Deceleration of the Complex Source and a Search for a Pulsar Nebula
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SN 1986J VLBI：复杂源的演化和减速以及脉冲星云的搜索
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
M. Rupen
中科院分区：
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作者：
M. Bietenholz;N. Bartel;M. Rupen
本文报道了旋涡星系NGC891的超新星1986J在爆炸后的两个新时期(1990年7月和1999年2月，t=7.4年和15.9年)的VLBI观测，并对这些观测和从爆炸后的t~4年开始的早期观测进行了综合分析，估计为1983.2±1.1.震源是壳体或复合材料，并继续显示出复杂的形态，沿脊线有很大的亮度调制，并有突起。超新星处于中等到强烈的减速状态。平均外半径膨胀为t0.71±0.11，膨胀速度从t=0.25时的2万公里S-1减慢到15.9年时的6000公里S-1。这种结构随时间发生显著变化，表明这种演化不是自相似的。壳体结构在最新时期最为明显，当时突起部分有所减弱，出现了一个新的、紧凑的组件。射电频谱显示在10 GHz以上有明显的反转。这可能与脉冲星星云通过爆炸的碎片变得可见有关。1.5~2 3 GHz射电通量密度随时间急剧减小，t~15a~19年的射电通量密度∝为-2.94±0.2 4。这一下降速度比更早的测量结果要快得多，直到t~6年。
We report on VLBI observations of supernova 1986J in the spiral galaxy NGC 891 at two new epochs, 1990 July and 1999 February, t = 7.4 and 15.9 yr after the explosion, respectively, and on a comprehensive analysis of these and earlier observations from t ~ 4 yr after the explosion date, which we estimate to be 1983.2 ± 1.1. The source is a shell or composite and continues to show a complex morphology with large brightness modulations along the ridge and with protrusions. The supernova is moderately to strongly decelerated. The average outer radius expands as t0.71±0.11, and the expansion velocity has slowed to 6000 km s-1 at t = 15.9 yr from an extrapolated 20,000 km s-1 at t = 0.25 yr. The structure changes significantly with time, showing that the evolution is not self-similar. The shell structure is best visible at the latest epoch, when the protrusions have diminished somewhat in prominence and a new, compact component has appeared. The radio spectrum shows a clear inversion above 10 GHz. This might be related to a pulsar nebula becoming visible through the debris of the explosion. The radio flux density between 1.5 and 23 GHz decreases strongly with time, with the flux density ∝t-2.94±0.24 between t ~ 15 and 19 yr. This decrease is much more rapid than that found in earlier measurements up to t ~ 6 yr.