L1551 IRS 5 中复杂有机分子的起源：热加热与吸积激波的相互作用
Origins of complex organic molecules in L1551 IRS 5: Interplay of thermal heating and accretion shocks
- Korea Astronomy and Space Science Institute（韩国天文与空间科学研究院）
- Department of Physics and Astronomy, Seoul National University（首尔大学物理与天文学系）
- Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University（鹿儿岛大学理工学研究科物理与天文学系）
- Academia Sinica Institute of Astronomy & Astrophysics（中央研究院天文及天文物理研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
利用ALMA数据，通过区分热加热与吸积激波，揭示了双星L1551 IRS 5中复杂有机分子源于辐射加热和局域激波，并展示了双模式吸积对盘化学结构的影响。
AI中文摘要：
复杂有机分子（COMs）通常在 Class 0 原恒星温暖的内部包层中被观测到。在演化程度更高的 Class I 源中，COM 发射被限制在致密的内部盘中，并被高尘埃不透明度所遮蔽，但 FU Orionis 型双星 L1551 IRS 5 为探测盘化学提供了宝贵的机会，因为其爆发光度将冰热升华至大半径处。我们试图在空间上分辨该系统中 COMs 的起源，以区分中心辐射加热与由异质吸积路径驱动的激波诱导化学。我们分析了高角分辨率 ALMA 档案数据，重点关注 COMs（如 CH3OH、CH3OCHO）和激波示踪剂 SO，并比较了它们的空间形态和运动学，以诊断与不同吸积流相关的激发条件。我们发现 L1551 IRS 5 中的 COM 发射既来自辐射加热，也来自局域吸积激波。在北源中，广泛分布的低激发 COM 发射主要与近期爆发产生的热加热一致。该源还表现出具有不同化学特征的双模式吸积，沿旋臂的 COMs 追踪了稳定的赤道环双星盘到环恒星盘吸积，而沿东盘面的高激发 COMs 和明亮 SO 则追踪了垂直包层到盘的流撞击。在南源中，甲醇被限制在东南流撞击点，而 SO 在潮汐截断半径处形成环状结构。我们将这种差异归因于不同的化学存活时间尺度。因此，L1551 IRS 5 是研究激波化学和双星调控吸积如何塑造原恒星盘化学结构的理想实验室。
英文摘要：
Complex organic molecules (COMs) are typically observed in the warm inner envelopes of Class 0 protostars. In more evolved Class I sources, COM emission is confined to the compact inner disk and obscured by high dust opacity, but the FU Orionis-type binary L1551 IRS 5 offers a valuable opportunity to probe disk chemistry, as its outburst luminosity thermally sublimates ices out to large radii. We sought to spatially resolve the origins of COMs in this system to distinguish between central radiative heating and shock-induced chemistry driven by heterogeneous accretion pathways. We analyzed high-angular-resolution ALMA archival data, focusing on COMs (e.g., CH3OH, CH3OCHO) and the shock tracer SO, and compared their spatial morphologies and kinematics to diagnose the excitation conditions associated with different accretion flows. We find that the COM emission in L1551 IRS 5 arises from both radiative heating and localized accretion shocks. In the northern source, the widespread low-excitation COM emission is primarily consistent with thermal heating by the recent outburst. This source also exhibits dual-mode accretion with distinct chemical signatures, with COMs along the spiral arm tracing steady equatorial circumbinary disk-to-circumstellar disk accretion and high-excitation COMs with bright SO along the eastern disk surface tracing a vertical envelope-to-disk streamer impact. In the southern source, methanol is confined to the southeastern streamer impact site, whereas SO forms a ring-like structure at the tidal truncation radius. We attribute this difference to differential chemical survival timescales. L1551 IRS 5 thus serves as an ideal laboratory to investigate how shock chemistry and binary-regulated accretion shape the chemical structure of protostellar disks.
