The Diffuse Ionized Gas Halo of the Small Magellanic Cloud
The Diffuse Ionized Gas Halo of the Small Magellanic Cloud
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DOI：
10.3847/1538-4357/ab4d58
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发表时间：
2019-11
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影响因子：
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通讯作者：
B. Smart;L. M. Haffner;K. Barger;Alex S. Hill;G. Madsen
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作者：
B. Smart;L. M. Haffner;K. Barger;Alex S. Hill;G. Madsen
利用威斯康星州制图仪进行的观测显示，小麦哲伦云（SMC）周围有一个大的、弥漫的电离晕。我们提出了第一次运动学调查的星系周围的一个扩展区域，从到覆盖。电离气体辐射远远超出了星系的中央恒星组成部分，达到类似的距离，由21厘米的观测跟踪的弥漫中性晕。发射延伸了几度，超出了目前H i调查的灵敏度，朝向更小的银河系赤道和更负的银河系纬度。SMC附近的电离气体的速度场似乎类似于星系的中性晕。使用观测到的发射测量作为指导，我们估计这个新发现的电离成分的质量大致是，这是可比的总中性质量在同一地区的。我们发现在三个不同的分区中总电离气体质量除以总中性加电离气体质量的比率为：（1）在SMC及其扩展晕中为46%-54%，（2）在SMC尾部向麦哲伦桥延伸的12%-32%，（3）在远离SMC向麦哲伦流延伸的灯丝中为65%-79%。这个新发现的相干细丝似乎没有结构良好的中性成分，并且与之前在流内通过21 cm发射追踪的两个确定的细丝也不一致。
Observations with the Wisconsin Mapper reveal a large, diffuse ionized halo that surrounds the Small Magellanic Cloud (SMC). We present the first kinematic survey of an extended region around the galaxy, from to and covering . The ionized gas emission extends far beyond the central stellar component of the galaxy, reaching similar distances to that of the diffuse neutral halo traced by 21 cm observations. emission extends several degrees beyond the sensitivity of current H i surveys toward smaller galactic longitudes and more negative galactic latitudes. The velocity field of the ionized gas near the SMC appears similar to the neutral halo of the galaxy. Using the observed emission measure as a guide, we estimate the mass of this newly revealed ionized component to be roughly , which is comparable to the total neutral mass in the same region of . We find ratios of the total ionized gas mass divided by the total neutral plus ionized gas mass in three distinct subregions to be: (1) 46%–54% throughout the SMC and its extended halo, (2) 12%–32% in the SMC Tail that extends toward the Magellanic Bridge, and (3) 65%–79% in a filament that extends away from the SMC toward the Magellanic Stream. This newly discovered, coherent filament does not appear to have a well-structured neutral component and is also not coincident with two previously identified filaments traced by 21 cm emission within the Stream.