RA: 19 h 27 m 26.6 s - DEC: +18 17' 45"
V=6.92 - Type: B7Ia

Comment: HD183143 is obscured by about five visual magnitude by interstellar clouds in the line-of-sight and present very strong Diffuse Interstellar Bands (DIB). The first DIB in stellar spectra were discovered in the 1920's (yellow 5780 and 5797 angstroms bands by M. L. Heger, 1922, Lick Obs. Bull., 10, 146), but their identification has remained a mystery for nearly 80 years. Recent work indicates that the origine for most DIB could be large carbon molecules in the interstellar gas. HD183143 is the archetypes of OB stars largely obscured by the dust of the interstellar medium (note the impressive reddening of the continuum). Spectrum of this interstellar medium contains a lot of information concerning the physical conditions inside HI clouds and the chemistry of these objects. I have identified in the following portion of HD183143 spectrum the principal DIB (green mark) and some stellar lines (bleue mark) (see G. H. Herbig, 1975, ApJ, 196, 129).


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