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

恒星形成是恒星演化中仅存的主要阶段，但人们对此仍知之甚少，特别是最早的演化阶段，当时新生恒星仍深深地嵌入其形成区域。对非常年轻的赫比格-哈罗恒星的物质流动的分析，特别是对高度准直的赫比格-哈罗喷流的子集的分析，提供了对支配恒星形成的吸积和质量损失过程的性质的间接但重要的见解。最近的研究为部分重建新生驱动源的物质抛射史以及它们的物质吸积史提供了可能。该项目正在完成对附近所有恒星形成区的主要干涉滤光片成像调查，以识别HerBig-Haro流，分析迄今已知的700多个HerBig-Haro流的特性，得出其统计特性，重复北方调查以获得流出的自行和能量，通过高分辨率光学和红外光谱研究喷流及其可见源的发射和准直区，获得物质流源的自适应光学辅助近红外图像和厘米无线电连续图，以便研究它们的多样性和测试喷流形成的情景，最后，一个先进的磁流体动力学程序模拟了激波的冷却区域，以更好地了解观测工作所发现的复杂形状和运动。对赫比格-哈罗流动的研究正在提供一个框架，可以在这个框架内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Haleakala的2米Faulkes望远镜(世界上最大的专门用于高中生教学的望远镜)，研究人员还提供了与这些喷气式飞机及其能源有关的小型研究项目。向公众传播这些成果的长期努力将继续通过讲座、天文学表演和在学校的演讲来进行。

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 the 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 jets and their energy sources. Long term efforts to disseminate these results to the public continue through talks, astronomy shows, and presentations at schools.