Collaborative Research: The Evolution of Winds in Dust Disks Around Stars

行星是由气体和尘埃盘中的物质形成的，这些物质曾经围绕着它们绕轨道运行的恒星。这些圆盘的形成方式以及物质在整个圆盘中的传播方式会影响物质添加到恒星本身的速度以及圆盘中可以形成的行星类型。盘风在这种材料的分散方式中发挥着重要作用。在这项研究中，研究人员以他们早期的工作为基础，观察了 33 个圆盘中的盘风。他们观察到风的两个部分：由磁/电相互作用驱动的风和由温差驱动的风。有了这笔资助，研究人员将扩大他们的研究范围，将大量更古老的磁盘纳入其中，目的是测量磁/电过程驱动风的程度以及热加热驱动风的程度。该项目符合国家利益，因为它扩展了我们对其他恒星周围行星系统形成背后的科学的理解。一名研究生、一名博士后和至少三名本科生将参加这项研究。调查人员还将参加亚利桑那大学举办的 K-12 教师研讨会，深入西班牙裔和美洲原住民社区。在一年一度的史密斯暑期科学与工程项目中，将向来自世界各地的高中女生教授为期两周的天文学课程。对金牛座 33 个圆盘的光学 [OI] 发射线的分析揭示了两个低速运动学分量，其中一个（宽分量）可能追踪磁流体动力学 (MHD) 驱动的风，而另一个（窄分量）可能与热驱动风相关。研究人员将通过测量 MHD 驱动风和热驱动风的相对比例，凭经验确定盘风如何演化。他们还将测量盘演化和扩散主要阶段的风质量损失率。他们将对 [OI] 线的分析扩展到更进化的圆盘样本，包括更多带有尘埃空腔的圆盘，并分析蓝色 [SII] 跃迁之一，以澄清对 [OI] 发射的热贡献。

Planets formed from material in disks of gas and dust that once surrounded the stars they orbit. The way that these disks form and how material is spread throughout the disks affect both how quickly material is added to the stars themselves and what types of planets can form in the disks. Disk winds play a major role in the way this material is dispersed. In this study, the investigators build on their earlier work where they observed the disk winds in 33 disks. They observed two parts to the winds: a wind driven by magnetic/electric interactions and a wind driven by temperature differences. With this grant the investigators will extend their study to include a large number of much older disks with the goals of measuring how much the magnetic/electric process drives with wind and how much the thermal heating drives the wind. This project serves the national interest as it expands our understanding of the science behind the formation of planetary systems around other stars. A graduate student, a postdoc, and at least three undergraduate students will participate in this study. The investigators will also participate in a K-12 teacher workshop at The University of Arizona, reaching Hispanic and Native American communities. A two-week long astronomy class will be taught to high school girls from around the world in the annual Smith Summer Science and Engineering Program. The analysis of optical [OI] emission lines for the 33 disks in Taurus reveals two low-velocity kinematic components, one of which (broad component) likely traces a magnetohydrodynamic (MHD)-driven wind while the other (narrow component) might be associated with a thermally-driven wind. The investigators will establish empirically how disk winds evolve by measuring the relative proportion of MHD-driven and thermally-driven winds. They will also measure wind mass loss rates through the main stages of disk evolution and dispersal. They will extend their analysis of the [OI] lines to a sample of more evolved disks, including more disks with dust cavities, and analyze one of the blue [SII] transitions to clarify the thermal contribution to the [OI] emission.