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，这些气体和尘埃曾经环绕着它们运行的恒星。这些圆盘的形成方式和物质在整个圆盘中的扩散方式既影响到物质添加到恒星本身的速度，也影响到圆盘中可以形成什么类型的行星。圆盘风在这种物质的分散方式中起着主要作用。在这项研究中，研究人员在他们早期工作的基础上，观察了33个圆盘的磁盘风。他们观察到了风的两个部分：由磁/电相互作用驱动的风和由温差驱动的风。有了这笔赠款，研究人员将扩大他们的研究范围，将大量更古老的圆盘包括在内，目标是测量磁/电过程有多少风驱动，以及热加热驱动风有多少。这个项目服务于国家利益，因为它扩大了我们对围绕其他恒星形成行星系统背后的科学的理解。一名研究生、一名博士后和至少三名本科生将参与这项研究。调查人员还将参加亚利桑那大学的K-12教师研讨会，接触拉美裔和美洲原住民社区。为期两周的天文学课程将在一年一度的史密斯夏季科学与工程项目中向世界各地的高中女生传授。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成分，其中一个(宽成分)可能跟踪了磁流体动力(MHD)驱动的风，而另一个(窄成分)可能与热驱动风有关。研究人员将通过测量磁流体驱动的风和热驱动的风的相对比例，从经验上确定盘状风是如何演变的。他们还将通过圆盘演化和扩散的主要阶段来测量风的质量损失率。他们将把他们对[OI]线的分析扩展到一个更进化的圆盘样本，包括更多带有尘埃空腔的圆盘，并分析其中一个蓝色的[SII]跃迁，以阐明[OI]排放的热贡献。

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.