Self broadening of hydrogen lines: initial results

For the first time broadening by both resonance and dispersive-inductive in teractions with H-atoms are included in the formation of Balmer lines in co ol stars, without the use of a multipole expansion. Comparison of synthetic profiles with observed profiles for the Sun and two late F dwarfs shows th at this improvement in broadening theory accounts for some of the problems found in previous work. It is anticipated that planned future developments in the theory of self broadening will lead to further improvements in the m odelling of cool star atmospheres.