猎户-波江超泡区域速度分辨的中性氢丝状结构与磁场取向关系

Velocity-resolved relationship between filamentary H Ⅰ structure and magnetic-field orientation in the Orion-Eridanus superbubble region

  • 摘要: 磁场和恒星反馈共同塑造着弥散星际介质的结构演化,而超泡环境中的气体动力学与磁场几何关系是其中的重要问题.先前研究表明,在通常为每秒几十到上百千米的较宽速度范围积分后,中性氢(H Ⅰ)丝状结构常与由尘埃偏振推断的天球面磁场取向保持一致.本文利用 FAST 联测巡天 CRAFTS 的 H Ⅰ数据和Planck 353 GHz 尘埃偏振数据,对猎户-波江超泡区域不同速度成分的 H Ⅰ结构与磁场取向关系进行了分析.研究中将 vLSR = −15~15 km·s−1 的 H Ⅰ发射划分为 6 个连续速度切片,并采用 rolling Hough transform(RHT)提取各速度切片中的丝状结构取向,再与尘埃偏振所追踪的磁场取向进行比较.结果表明:随速度变化,H Ⅰ发射亮度和丝状结构形态均发生系统变化;在超泡投影外侧区域,负速度成分与磁场取向之间存在空间上连续的较大偏差,而正速度成分则表现出更强的一致性;相比之下,超泡投影内侧区域随速度变化的差异较小.该结果说明,在猎户-波江超泡邻近环境中,不同速度成分并不遵循一致的 H Ⅰ-磁场取向关系,宽速度积分下常见的整体一致性并不能代表同一视线中所有的运动学成分.其中,超泡投影外侧负速度范围内空间连续的大角度差结构,提示该区域存在一类与周边主导成分几何关系不同的特殊原子气成分,为理解复杂反馈环境中不同原子气成分的形成与演化提供了新的观测线索.

     

    Abstract: Magnetic fields are a fundamental property of diffuse interstellar medium. Previous studies have shown that filamentary H Ⅰ structure often follows the plane-of-sky magnetic field inferred from polarized dust emission. Leveraging high-sensitivity FAST/CRAFTS H Ⅰ survey and Planck 353 GHz dust polarization, we target the Orion-Eridanus superbubble environment and map relative orientation between H Ⅰ filaments and dust-inferred magnetic field across vLSR = −15 to 15 km·s−1. We find a clear environmental bifurcation: exterior to the projected shell, low-velocity gas (−15 ≤ vLSR < 0 km·s−1) shows large and spatially coherent misalignment, whereas higher-velocity exterior gas aligns significantly better. The interior remains comparably well-aligned across all velocities, with little velocity dependence. Therefore broad H Ⅰ-dust alignment commonly seen in velocity-integrated studies does not apply uniformly to all kinematic components in the Orion-Eridanus environment. The spatially coherent low-velocity exterior structure represents a distinct component with enhanced misalignment, providing a new observational clue to the origin of geometrically differentiated atomic gas in a feedback-shaped environment.

     

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