The origin of broad emission lines in the extragalactic giant H II region NGC 2363
The origin of broad emission lines in the extragalactic giant H II region NGC 2363
复制标题
河外巨型 H II 区域 NGC 2363 宽发射线的起源
DOI：
10.1086/171035
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
R. Dufour
中科院分区：
文献类型：
--
作者：
J. Roy;M. Aubé;M. McCall;R. Dufour
位于矮SBM星系NGC2366中的巨型HⅡ区NGC2363获得了高信噪比的长缝光谱。本文报道了在明亮的星云线H-α、H-β和禁带O III中发现了低强度的广谱成分(半高宽约等于40A或2400公里/S)。在以星云为中心的大空间范围内(不低于500pC)，可以探测到宽光谱分量。探索了几种加宽星云线条的机制：恒星风、热气体的汤姆森散射、超新星遗迹和超泡喷发。所有的机制都有问题。超泡爆发是已知的唯一一种能够在如此大的空间中加速星际气体的机制，它似乎与H II区NGC 2363的物理性质或宿主星系的性质不一致。这些宽阔的星云线条很可能是由于非常高速度的气体造成的，其来源目前尚不清楚。
High signal-to-noise long-slit spectra have been obtained of the giant H II region NGC 2363 located in the dwarf SBm galaxy NGC 2366. A discovery of low-intensity broad spectral components (FWHM is approximately equal to 40 A or 2400 km/s) in the bright nebular lines H-alpha, H-beta, and forbidden O III is reported. The broad spectral components are detected over a large spatial extent (not less than 500 pc) centered on the nebula. Several mechanisms for broadening nebular lines are explored: stellar winds, Thomson scattering by hot gas, supernova remnants, and superbubble blowout. All mechanisms have problems. Superbubble blowout, which is the only known mechanism capable of accelerating interstellar gas over such a volume of space, does not appear consistent with the physical properties of the H II region NGC 2363 or with the nature of the host galaxy. It is concluded that the broad nebular lines are probably due to very high velocity gas whose origin is, at present, unknown.