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arXiv 1503.01135astro-ph.GA
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M81和M82中超新星遗迹的光谱学

Optical Spectroscopy of Supernova Remnants in M81 and M82

Myung Gyoon Lee, Jubee Sohn, Jong Hwan Lee, Sungsoon Lim, In Sung Jang, Youkyung Ko, Bon-Chul Koo, Narae Hwang, Sang Chul Kim, Byeong-Gon Park

摘要:

我们目前的光谱28 SNR候选人,以及一个H II区域在M81,和两个SNR候选人在M82。在M81的候选者中,有26个被证明是真正的SNRs,而M82中的两个可能是星系外流中的激波凝聚或SNRs。M81信噪比的[N Ⅱ]/Hα比值呈双峰分布。在谱线比值图上,M81的信噪比可分为两组:[O III]-强群和[O III]-弱群。后者具有较大的尺寸,并且可能具有更快的冲击速度。信噪比的[N Ⅱ]/Hα比值与[S Ⅱ]/Hα比值有很强的相关性。它们在[N II]/Hα和[S II]/Hα比值中显示出明显的径向梯度:dLog([N II]/Hα)/dLog R = -0.018 { \pm } 0.008 dex/kpc和dLog([S II]/Hα)/dLog R = -0.016 { \pm } 0.008 dex/kpc,其中R是去投影的银河系中心距。我们估计的氮和氧的丰度的SNR从冲击电离模型的比较。我们得到了氮径向梯度的值dLog(N/H)/dLogR = -0.023 { \pm } 0.009 dex/kpc,而氧中的梯度几乎没有证据。这个氮丰度的梯度比行星状星云和H II区的要平坦几倍。我们发现,五个SNR与X射线源相匹配。它们的X射线硬度颜色与热SNR一致。

英文摘要:

We present spectroscopy of 28 SNR candidates as well as one H II region in M81, and two SNR candidates in M82. Twenty six out of the M81 candidates turn out to be genuine SNRs, and two in M82 may be shocked condensations in the galactic outflow or SNRs. The distribution of [N II]/Hα ratios of M81 SNRs is bimodal. M81 SNRs are divided into two groups in the spectral line ratio diagrams: an [O III]-strong group and an [O III]-weak group. The latter have larger sizes, and may have faster shock velocity. [N II]/Hα ratios of the SNRs show a strong correlation with [S II]/Hα ratios. They show a clear radial gradient in [N II]/Hα and [S II]/Hα ratios: dLog ([N II]/Hα)/dLog R = -0.018 {\pm} 0.008 dex/kpc and dLog ([S II]/Hα)/dLog R = -0.016 {\pm} 0.008 dex/kpc where R is a deprojected galactocentric distance. We estimate the nitrogen and oxygen abundance of the SNRs from the comparison with shock-ionization models. We obtain a value for the nitrogen radial gradient, dLog(N/H)/dLogR = -0.023 {\pm} 0.009 dex/kpc, and little evidence for the gradient in oxygen. This nitrogen abundance shows a few times flatter gradient than those of the planetary nebulae and H II regions. We find that five SNRs are matched with X-ray sources. Their X-ray hardness colors are consistent with thermal SNRs.

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