Collaborative Research: Herbig-Haro Flows as Probes of Early Stellar Evolution

恒星形成是恒星演化过程中唯一遗留下来的主要阶段，人们对这一阶段仍然知之甚少，尤其是在最初的演化阶段，那时新生的恒星仍深埋在它们形成的区域中。对来自非常年轻的赫比格-哈罗恒星的物质流的分析，特别是对高度准直的赫比格-哈罗射流子集的分析，为了解控制恒星形成的吸积和质量损失过程的本质提供了间接但重要的见解。最近的研究为部分重建新形成的驱动源的物质抛射史以及它们的物质吸积史提供了可能。该项目正在完成对所有附近恒星形成区域的主要干涉滤光成像调查，以确定赫比格-哈罗流，分析迄今为止已知的700多个赫比格-哈罗流的特性以得出其统计特性，重复其北部调查以获得流出物的适当运动和能量学，通过高分辨率光学和红外光谱研究射流的发射和准直区域及其可见源。获得自适应光学辅助的近红外图像和厘米射电连续图的物质流来源，以研究其多样性和测试射流形成场景，最后，一个先进的磁流体动力学代码模拟激波的冷却区域，以便更好地理解观测工作所揭示的复杂形状和运动。更广泛的影响:。赫比格-哈罗流的研究提供了一个框架，在这个框架内可以解释其他类型的天体物理喷流。这项研究继续涉及研究生和本科生。通过哈雷阿卡拉的2米福克斯望远镜（世界上最大的专门用于高中教学的望远镜），研究人员还提供了与这些物质流及其能量来源相关的小型研究项目。通过讲座、天文表演和在学校的演讲，向公众传播这些成果的长期努力仍在继续。

Star formation is the only remaining major phase of stellar evolution that is still poorly understood, especially the very earliest evolutionary stages when the nascent stars are still deeply embedded in the regions of their formation. Analysis of material flows from the very young Herbig-Haro stars, and in particular of the subset of highly collimated Herbig-Haro jets, provide indirect but important insights into the nature of the accretion and mass loss processes which govern the formation of stars. The recent studies open the possibility to partially reconstruct the mass ejection history of the newly born driving sources and therefore their mass accretion history. This project is completing a major interference filter imaging survey of all nearby star forming regions in order to identify Herbig-Haro flows, analyzing the properties of the more than 700 Herbig-Haro flows known so far to derive their statistical properties, repeating their northern survey to obtain proper motions and energetics of the outflows, studying the launch and collimation regions of jets and their visible sources by high resolution optical and infrared spectroscopy, obtaining adaptive optics assisted near-infrared images and centimeter radio continuum maps of the sources of material flows in order to study their multiplicity and to test jet formation scenarios, and finally, an advanced magnetohydrodynamical code simulates the cooling regions of the shocks for a better understanding of the complex shapes and motions uncovered by the observational efforts.Broader impact:. The study of Herbig-Haro flows is providing a framework within which other classes of astrophysical jets may be interpreted. This research continues to involve both graduate and undergraduate students. Through the 2 meter Faulkes telescope at Haleakala (the world's largest telescope exclusively dedicated to teaching high school students), the investigators also offer small research programs related to these material flows and their energy sources. Long term efforts to disseminate these results to the public continue through talks, astronomy shows, and presentations at schools.