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arXiv 1202.3156astro-ph.GAastro-ph.CO
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M51中SN 2011 dh的星际钠和钙吸收

Interstellar Sodium and Calcium Absorption toward SN 2011dh in M51

Adam M. Ritchey, George Wallerstein

摘要:

我们提出了SN 2011 dh的高分辨率阶梯观测,它在附近爆炸,几乎面对面的螺旋星系M51。我们的数据,获得了三个晚上的超新星时,接近最大亮度,揭示了多个吸收成分在钠I D和钙II H和K,我们确定与气态物质在银河系盘或低晕和磁盘和晕的M51。M51分量的速度范围超过140 km/s,远远超出了超新星位置H I 21 cm辐射所显示的范围。由于没有一个显著的Na I或Ca II成分与H I发射峰相一致,超新星可能正好位于H I盘的前面。Na I/Ca II的比例与最极端的积极和消极的速度相对于磁盘的组件是~1.0,类似于那些更静态的组件,这表明吸收起源于相对较冷的气体。涉及银河喷泉和/或M51与其伴星之间的潮汐相互作用的生产情景与这些结果一致。在SN 2011 dh方向上Na I D吸收的整体弱点证实了超新星的低前景和宿主星系灭绝。

英文摘要:

We present high-resolution echelle observations of SN 2011dh, which exploded in the nearby, nearly face-on spiral galaxy M51. Our data, acquired on three nights when the supernova was near maximum brightness, reveal multiple absorption components in Na I D and Ca II H and K, which we identify with gaseous material in the Galactic disk or low halo and in the disk and halo of M51. The M51 components span a velocity range of over 140 km s^-1, extending well beyond the range exhibited by H I 21 cm emission at the position of the supernova. Since none of the prominent Na I or Ca II components appear to coincide with the peak in H I emission, the supernova may lie just in front of the bulk of the H I disk. The Na I/Ca II ratios for the components with the most extreme positive and negative velocities relative to the disk are ~1.0, similar to those for more quiescent components, suggesting that the absorption originates in relatively cool gas. Production scenarios involving a galactic fountain and/or tidal interactions between M51 and its companion would be consistent with these results. The overall weakness of Na I D absorption in the direction of SN 2011dh confirms a low foreground and host galaxy extinction for the supernova.

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