The diffuse interstellar bands. IX - Constraints on the identification

Measurements of the equivalent widths of the diffuse interstellar bands (DIBs) 5780, 5797 AA and of the interstellar D1 and D2 lines, which were performed on Lick and Canada-France-Hawaii Telescope coude spectrograms of 93 stars, are presented. The carrier of the 5780, 5797-AA DIBs is not produced by the processes based on H2 that control the abundance of the carbon diatomics. There is no evidence that the carrier is affected in a systematic way by the degree of depletion of Ti, believed to be an indicator of whether the solid grains have been shocked or not. The carrier is not affected by the shock heating of the gas that is believed to be responsible for the presence of strong CH(+) in some clouds. There is a clear power-law dependence of DIB strength on the column density of HI, but with a breakdown at high N(H I). There is also a power-law dependence, but with a smaller exponent, upon the column densities of Na I, KI, and C I.

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