On correlations between diffuse interstellar bands

One way to better apprehend the problem of diffuse interstellar bands (DIBs) is to search for correlations between the bands in a large sample of spectra towards various lines of sight: a strict correlation may imply that a common carrier is at the origin of the bands, whereas a non-correlation means that different species are involved. We propose this observational test for 10 DIBs collected in up to 62 Galactic lines of sight. Strong DIBs do not strictly correlate, and sometimes the correlation is very poor. Only one example of a strict correlation has been found in our sample between the DIBs at 6614 and 6196 Å, that could signify a single carrier for those two bands. The general absence of strict correlations is discussed in the context of molecular carriers for the DIBs.