Large Line Widths in HH Objects - The Bow Shock Model

Abstract

The line widths of Herbig-Haro objects sometimes exceed 400 km s–1 within an object only about 1500 AU in size. Many of the line profiles are double-peaked, with the stronger of the two peaks occurring near zero radial velocity. These unusual spectral characteristics together with the observed mixture of high and low excitation lines provide essential clues to the geometry and physics of the radiative shocks responsible for the emission. In this paper the predictions of a radiative bow shock model are briefly reviewed, with special emphasis placed on the explanation of broad-lined HH objects.