原行星盘多样样本中分子离子分布的测绘
Mapping Molecular Ion Distributions in a Diverse Sample of Protoplanetary Disks
- University of Virginia（弗吉尼亚大学）
- University of Minnesota（明尼苏达大学）
- University of Michigan（密歇根大学）
- U.S. Naval Academy（美国海军学院）
- Harvard-Smithsonian Center for Astrophysics（哈佛-史密森天体物理中心）
- Columbia University（哥伦比亚大学）
- Wesleyan University（卫斯理安大学）
- Boston University（波士顿大学）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本研究利用ALMA观测七个原行星盘中的分子离子，发现离子分布与连续谱无强关联，但揭示Herbig与T-Tauri源的电离环境差异及潜在二分性，使解析离子观测数量翻倍。
中文摘要 AI 辅助
对原行星盘中电离示踪分子的观测表明，由于宇宙射线调制程度、恒星活动以及改变电离辐射影响的环境差异，它们的电离环境是多样的。为了更好地理解盘中的电离化学，我们展示了迄今为止对分子离子进行解析观测的最大规模巡测。利用新的和存档的ALMA观测数据，我们在七个原行星盘（AS 209、DM Tau、GM Aur、HD 163296、LkCa 15、MWC 480和V4046 Sgr）中探测到了HCO+、H13CO+、N2H+和DCO+。我们将离子分布与连续谱特征进行比较，发现两者之间没有稳健的关系。然而，观测确实揭示了Herbig星与T-Tauri星之间的区别，并暗示了两种T-Tauri电离环境之间的二分性。Herbig源表现出独特的中心峰值N2H+ J = 4-3发射，我们推测这可能追踪了高度电离的表面层或CO破坏区域，可能是由于其强烈的紫外场。我们样本中的三个T-Tauri源在所有光学薄分子离子谱线中表现出明亮的、径向重合的环。我们推测这些径向重合的离子环是电离发生全局变化的证据，可能位于T-Tauri球层的边缘。虽然目前尚不清楚哪些因素对离子发射分布的影响最为强烈，但这项巡测使盘中解析离子观测的数量增加了一倍以上，并指出了与中心恒星和环境相关的离子发射形态的潜在差异。
英文摘要
Observations of ionization-tracing molecules in protoplanetary disks suggest that their ionization environments are diverse due to varying degrees of cosmic ray modulation, stellar activity, and environmental differences that alter the impact of ionizing radiation. To better understand ionization chemistry in disks, we present the largest survey of resolved observations of molecular ions to date. Using new and archival ALMA observations we detect HCO+, H13CO+, N2H+, and DCO+ toward seven protoplanetary disks (AS 209, DM Tau, GM Aur, HD 163296, LkCa 15, MWC 480, and V4046 Sgr). We compare distributions of ions to continuum features and find no robust relationships between the two. The observations do, however, reveal distinctions between Herbigs and T-Tauris and hint at a dichotomy between two types of T-Tauri ionization environments. The Herbig sources exhibit unique centrally-peaked N2H+ J = 4-3 emission, which we speculate could be tracing either a highly ionized surface layer or a zone of CO destruction, possibly due to their strong UV fields. Three T-Tauri sources in our sample exhibit bright, radially coincident rings in all optically thin molecular ion lines. We speculate that these radially coincident ion rings are evidence of a global change in ionization, possibly at the edge of a T-Tauriosphere. While it is not yet clear what factors most strongly influence the distribution of ion emission, this survey more than doubles the number of resolved ion observations in disks and points to potential distinctions in ion emission morphology related to the central star and environment.
