Herbig-Haro Objects

Abstract

After a brief introductory discussion of the statistics of known Herbig-Haro (HH) objects we present a survey of recent spectroscopic results in the ultraviolet, the optical and the near infrared range (the latter mostly in connection with H2 observations). We emphasize the importance of the use of spatially resolved line profiles (position-velocity diagrams) in the optical range for the purpose of testing hydrodynamic models of HH objects. Such observations have now been supplemented by the measurement of spatially dependent intensity ratios for a large number of optical lines ~200 in HH 1) and of some ultraviolet lines (including fluorescent H2 lines) which are very useful for diagnostic purposes. The relevance and importance of spectroscopy and imaging in the infrared H2 lines is discussed.