Excited Hydroxyl Outflow in the High-mass Star-forming Region G34.26 + 0.15
Excited Hydroxyl Outflow in the High-mass Star-forming Region G34.26 + 0.15
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DOI：
10.3847/1538-4357/acde7b
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发表时间：
2023-06
期刊：
影响因子：
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通讯作者：
W. S. Tan;E. Araya;Cade Rigg;P. Hofner;S. Kurtz;H. Linz;V. Rosero
中科院分区：
文献类型：
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作者：
W. S. Tan;E. Araya;Cade Rigg;P. Hofner;S. Kurtz;H. Linz;V. Rosero
G34.26 + 0.15是一个高质量星星形成区，包含了大量处于不同演化阶段的年轻恒星，包括一个热分子核心、超致密H ii区和一个典型的彗星超致密H ii区。我们小组先前的高灵敏度单碟观测导致在该区域检测到宽6035 MHz OH吸收;该线显示出显着的蓝移不对称性，表明分子气体膨胀。我们提出了高灵敏度的卡尔G。Jansky甚大阵列（VLA）对6035 MHz OH线进行了观测，以成像吸收并调查其相对于该地区不同星星形成地点的起源。此外，我们报告检测6030 MHz的OH吸收与VLA和进一步观察4.7 GHz和6.0 GHz的OH线获得的阿雷西博望远镜。6030 MHz OH线显示出与6035 MHz OH线非常相似的吸收曲线。我们发现6035 MHz OH线吸收区在0.2 ″尺度上是空间不可分辨的，它与彗星H ii区的一个明亮的电离核相一致，该核显示出宽的射电复合线发射。我们讨论的情况下，OH的吸收是跟踪残余的一个极上的分子流出，被电离的内部由ultracompact H II区域。
G34.26 + 0.15 is a region of high-mass star formation that contains a broad range of young stellar objects in different stages of evolution, including a hot molecular core, hypercompact H ii regions, and a prototypical cometary ultracompact H ii region. Previous high-sensitivity single-dish observations by our group resulted in the detection of broad 6035 MHz OH absorption in this region; the line showed a significant blueshifted asymmetry indicative of molecular gas expansion. We present high-sensitivity Karl G. Jansky Very Large Array (VLA) observations of the 6035 MHz OH line conducted to image the absorption and investigate its origin with respect to the different star formation sites in the region. In addition, we report detection of 6030 MHz OH absorption with the VLA and further observations of 4.7 GHz and 6.0 GHz OH lines obtained with the Arecibo Telescope. The 6030 MHz OH line shows a very similar absorption profile as the 6035 MHz OH line. We found that the 6035 MHz OH line absorption region is spatially unresolved at ∼2″ scales, and it is coincident with one of the bright ionized cores of the cometary H ii region that shows broad radio recombination line emission. We discuss a scenario where the OH absorption is tracing the remnants of a pole-on molecular outflow that is being ionized inside-out by the ultracompact H ii region.