A high-resolution study of Herbig-Haro objects 1 and 2

Observations have been conducted of Herbig-Haro objects 1 and 2 with high spectral and spatial resolution in order to test shock models for the line emission. A detailed bow shock model has been constructed which yields line widths and optical and UV spectra in reasonable agreement with observation for maximum shock velocities approximately 200 km/s. Such velocities are comparable to the transverse velocities of the knots in HH 1 and 2 inferred from proper motion studies. The observations suggest that HH objects are rapidly moving, dense clouds shocking with less dense interstellar medium. The large energy requirements of these objects, combined with their small apparent size as seen from the exciting star, seem to require unreasonably large stellar mass loss rates. However, it is possible that the HH objects subtended a much larger solid angle at the star when originally accelerated.