A Search for Narrow Vertical Structures in the Canadian Galactic Plane Survey
A Search for Narrow Vertical Structures in the Canadian Galactic Plane Survey
复制标题
加拿大银河平面巡天中寻找狭窄垂直结构
DOI：
10.1086/431478
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
R. Kothes
中科院分区：
文献类型：
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作者：
A. Asgekar;J. English;S. Safi;R. Kothes
蠕虫被定义为尘埃，原子氢（H I）结构，在低分辨率数据中观察到垂直于银河平面上升。利用加拿大银道面巡天（CGPS）1′分辨率的观测资料，系统地寻找了能分辨蠕虫的垂直窄H I结构。搜索的另一个动机是探索蘑菇状蠕虫（如由英语和合作者研究的GW 123.4-1.5）可能由单个超新星产生的场景。我们还检查了Koo和合作者先前分类为蠕虫候选者的对象;只有7个对象的结构的重要部分落在CGPS范围内，l = 74°-147°，-3. ° 5 < B < +5. ° 5。除了GW 123.4-1.5之外，我们无法确认其中任何一个是向银河系晕延伸的相干结构。然而，在我们的搜索中发现的10个狭窄的垂直结构的列表是提供的;一个结构是1500 pc高，因此从银河平面延伸到晕。我们提供这些狭窄的垂直结构的细节，包括H I，无线电连续谱，IR和CO观测之间的比较。我们的搜索进行了目视检查，我们描述了这种方法的局限性，因为它表明，只有6盘晕功能可能存在于整个银河系。我们还讨论了高纬度地区结构的可能起源以及蘑菇状云和古老超新星遗迹之间的关系。
Worms are defined to be dusty, atomic hydrogen (H I) structures that are observed in low-resolution data to rise perpendicular to the Galactic plane. Data from the 1′ resolution Canadian Galactic Plane Survey (CGPS) were systematically searched for narrow vertical H I structures that could be resolved worms. Another motivation for the search was to explore the scenario in which mushroom-shaped worms such as GW 123.4-1.5, studied by English and collaborators, could be generated by a single supernova. However, no other vertical structures of mushroom-shape morphology were found. We also examined objects previously classified as worm candidates by Koo and collaborators; only seven have a significant portion of their structure falling in the CGPS range of l = 74°–147°, -3.°5 < b < +5.°5. Apart from GW 123.4-1.5, we could not confirm that any of these are coherent structures that extend toward the Milky Way's halo. However, a list of 10 narrow vertical structures found in our search is furnished; one structure is ≳500 pc tall, thus extending from the Galactic plane into the halo. We provide details about these narrow vertical structures, including comparisons between H I, radio continuum, IR, and CO observations. Our search was conducted by visual inspection, and we describe the limitations of this approach since it indicates that only six disk-halo features may exist throughout the Milky Way. We also discuss the possible origins of structures at high latitudes and the relationship between mushroom-shaped clouds and old supernova remnants.