CN (3,0) red system features in interstellar translucent clouds

Abstract

We report observations of four weak absorption lines of the interstellar CN A2Π-X2∑+ (3,0) band: R1(0) 6951.8 Å, RQ21(0) 6927.3 Å, R2(1)+RQ1(1) 6926.7 Å, QR1(1)+Q1(1) 6953.6 Å, and show that they provide reasonable information on column densities in sightlines towards early-type stars. The (3,0) band is always very weak and thus the saturation effect is negligible, which is particularly useful for the sightlines where the near UV-range CN bands are very strong, i.e. saturated. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.