Supersonic Expansion of the Bipolar H ii Region Sh2-106: A 3500 Year Old Explosion?
Supersonic Expansion of the Bipolar H ii Region Sh2-106: A 3500 Year Old Explosion?
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DOI：
10.3847/1538-4357/ac30de
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发表时间：
2021-11
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影响因子：
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通讯作者：
J. Bally;Zen H. Chia;A. Ginsburg;B. Reipurth;Kei E. I. Tanaka;H. Zinnecker;J. Faulhaber
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作者：
J. Bally;Zen H. Chia;A. Ginsburg;B. Reipurth;Kei E. I. Tanaka;H. Zinnecker;J. Faulhaber
对双极H II区Sh2 - 106进行的多历元哈勃太空望远镜窄带图像观测显示，星云的自行速度极高且超音速，其速度随与大质量年轻恒星天体S106 IR的投影距离增加而增大，在距S106 IR约1.′4（0.44 pc，1 pc = 3.086×10¹⁶ m）的投影间距处达到约30 mas yr⁻¹（在D = 1.09 kpc处约为150 km s⁻¹，1 kpc = 3.086×10¹⁹ m）。我们提出S106 IR在约3500年前经历了一次约10⁴⁷ erg的爆发。这次爆发可能是一次大规模吸积爆发的结果，或者是近期与另一颗恒星相遇所致，也可能是在S106 IR以高吸积率从约10 M⊙增长到约15 M⊙的过程中，伴星与S106 IR膨胀的光球层相互作用的结果。近红外图像显示H₂发射指状物背离S106 IR，并且在电离星云周围存在一个不对称的光子主导区域。射电连续谱和Brγ发射显示等离子体呈C形弯曲，这表明要么是S106 IR向东运动，要么是周围的云使等离子体向西偏转。H II区在S106 IR以西围绕一个直径约1′的暗湾弯曲，该暗湾可能被一个致密的分子团块遮挡而免受直接光照。还讨论了追踪由Sh2 - 106原星团中的恒星（如0级源S106 FIR）驱动的外流的赫比格 - 哈罗天体和分子氢天体。
Multi-epoch narrowband Hubble Space Telescope images of the bipolar H ii region Sh2-106 reveal highly supersonic nebular proper motions that increase with projected distance from the massive young stellar object S106 IR, reaching over ∼30 mas yr−1 (∼150 km s−1 at D = 1.09 kpc) at a projected separation of ∼1.′4 (0.44 pc) from S106 IR. We propose that S106 IR experienced a ∼1047 erg explosion ∼3500 yr ago. The explosion may be the result of a major accretion burst or a recent encounter with another star, or a consequence of the interaction of a companion with the bloated photosphere of S106 IR as it grew from ∼10 through ∼15 M ⊙ at a high accretion rate. Near-IR images reveal fingers of H2 emission pointing away from S106 IR and an asymmetric photon-dominated region surrounding the ionized nebula. Radio continuum and Brγ emission reveal a C-shaped bend in the plasma, indicating either the motion of S106 IR toward the east, or the deflection of plasma toward the west by the surrounding cloud. The H ii region bends around a ∼1′ diameter dark bay west of S106 IR that may be shielded from direct illumination by a dense molecular clump. Herbig–Haro and Molecular Hydrogen Objects tracing outflows powered by stars in the Sh2-106 protocluster such as the Class 0 source S106 FIR are discussed.