NEW PARAMETRIZATIONS OF NON-GAUSSIAN LINE-OF-SIGHT VELOCITY DISTRIBUTION

A five-parameter fitting formula for the line-of-sight stellar velocit y distributions (LOSVDs) of steady-state systems is proposed. It can f aithfully reproduce velocity distributions of theoretical models rangi ng from nearly Gaussian profiles to strongly skewed or mildly double-p eaked profiles. In contrast to the assumptions of van der Marel & Fran x and Kuijken & Merrifield, the LOSVDs are required to have neither mu ltipeaks nor negative velocity wings and most information can be recov ered from no more than five physically meaningful fitting parameters.