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.
