Forward Shock Proper Motions of Kepler’s Supernova Remnant
Forward Shock Proper Motions of Kepler’s Supernova Remnant
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DOI：
10.1086/592376
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发表时间：
2008-12
期刊：
影响因子：
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通讯作者：
S. Katsuda;H. Tsunemi;H. Uchida;M. Kimura
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文献类型：
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作者：
S. Katsuda;H. Tsunemi;H. Uchida;M. Kimura
开普勒超新星遗迹的X射线结构显示出由前向冲击所描绘的圆形。我们测量的自行的前向冲击的整体边缘的残留物，使用档案钱德拉数据采取的两个时代的时间差为6.09年。测得北方边缘前向激波的自行为0.076″（±0.032″ ±0.016″）至0.11″（±0.014″ ±0.016″）yr−1，而其余轮辋上的测量值为0.15″（±0.017″ ±0.016″）到0.30″（±0.048″ ±0.016″）yr−1;这里第一项误差是统计不确定性，第二项误差是系统不确定性。在遗迹的北方和中部测得的巴尔末主导的暗条的最佳估计激波速度为1660 ± 120 km s−1（Sankrit et al. 2005），结合北方边缘前向激波的自行，我们估计到遗迹的距离为3.3+1.6−0.4 kpc。我们测量的膨胀指数，m（定义为R tm），为0.47-0.82的大部分轮辋。这些值与Ia型超新星爆炸模型中预期的值一致，在Ia型超新星爆炸模型中，喷出物和星周介质具有指数分别为5-7和0-2的幂律密度分布。此外，我们应该注意到，北方边缘的扩张速度比南部边缘慢。这可能是由于星周介质的不均匀性造成的，星周介质的密度在遗迹的北部比南部高。新估计的几何中心，我们认为爆炸点存在于其周围，位于射电中心以北约5″的偏移处。
The X-ray structure of Kepler’s supernova remnant shows a rounded shape delineated by forward shocks. We measure proper motions of the forward shocks on overall rims of the remnant, by using archival Chandra data taken in two epochs with time difference of 6.09 yr. The proper motions of the forward shocks on the northern rim are measured to be 0.076″ (±0.032″ ±0.016″) to 0.11″ (±0.014″ ±0.016″) yr−1, while those on the rest of the rims are measured to be 0.15″ (±0.017″ ±0.016″) to 0.30″ (±0.048″ ±0.016″) yr−1; here the first-term errors are statistical uncertainties and the second-term errors are systematic uncertainties. Combining the best-estimated shock velocity of 1660 ± 120 km s−1 measured for Balmer-dominated filaments in the northern and central portions of the remnant (Sankrit et al. 2005) with the proper motions derived for the forward shocks on the northern rim, we estimate a distance of 3.3+1.6−0.4 kpc to the remnant. We measure the expansion indices, m (defined as R ∝ tm), to be 0.47-0.82 for most of the rims. These values are consistent with those expected in Type Ia SN explosion models, in which the ejecta and the circumstellar medium have power-law density profiles whose indices are 5-7 and 0-2, respectively. In addition, we should note the slower expansion on the northern rim than that on the southern rim. This is likely caused by the inhomogeneous circumstellar medium; the density of the circumstellar medium is higher in the north than that in the south of the remnant. The newly estimated geometric center, around which we believe the explosion point exists, is located at ~5″ offset to the north of the radio center.