Excitation temperature of C2 and broadening of the 6196 Å diffuse interstellar band

This paper presents a finding of the correlation between the width of a strong diffuse interstellar band at 6196 A and the excitation temperature ofC2 based on high resolution and high signal-to-noise ratio spectra. The excitation temperature was determined from absorption lines of the Phillips A 1 Πu − X 1 Σ + and Mulliken D 1 Σ + − X 1 Σ + systems. The width and shape of the narrow 6196 A DIB profile