Multi-epoch optical velocities of bright carbon stars

Abstract

Cross-correlated optical radial velocities are presented of 87 bright carbon stars, 67 with multiple epochs, as well as the velocities of atomic transitions of K I, Li I, and Mg I. The mean optical velocity variation is about 3 km/s for SR and Lb variables and 8.7 km/s for Miras. The spread in velocities among atomic lines at a given epoch is significantly greater in Miras than in SR and Lb variables. Although Li I shows significant velocity variation in Miras, K I is more stable. Thirteen of 33 carbon stars with H-alpha emission also show bright Mg I emission in a type of inverse P-Cygni profile, and each of these 13 stars shows a clear splitting of the K I resonance line. Only two stars, R For and CL Mon, show K I as P-Cygni profile. J-type carbon stars have deeper Li absorption profiles than other carbon stars in the sample.