Observations of spectral line asymmetries and convective velocities in F, G and K stars.

Line asymmetries are found to exist generally in F, G, and K stars. Line bisectors were measured for 11 relatively unblended lines in each of 27 stars, and an average line bisector was determined for each star. The average bisectors show systematic changes in velocity span and shape with spectral type. The bisector characteristics are interpreted in terms of granulation-type motion. Convective velocities are deduced as a function of spectral type. Values of approximately 3 times solar are seen in F5IV and V, in G0 III, and in K4 III stars. Minimum convective velocities occur near G8 with a value of approximately 0 for luminosity types IV and V but near the solar value for type III. The height of penetration of convection is found to be lowest in solar-type stars with convection essentially dying out before reaching the top of their photospheres. In nonsolar-type stars, larger convective velocities produce greater height penetration.