Three families of diffuse interstellar bands?

Abstract

The intensities of 10 of the yellow/red and the 4430 A diffuse interstellar bands (DIBs) and the broad 2200 A feature of the high Galactic latitude star Zeta Persei are compared with those for three other stars using high SNR spectra of either 1.1 A or 0.15 A resolution. The DIBs in Zeta Persei appear to fall into three well-defined groups: (1) 4430 and 6180 A are absent; (2) 5780, 6196, 6203, 6269, and 6284 A are about one-third the strength expected for the color excess; and (3) the 2200 A feature and the 5797, 5850, 6376, 6379, and 6614 A are of approximately normal strength for the color excess. This suggests that the DIBs may be caused by at least three agents where proportions vary from cloud to cloud. It is noted that other stars with markedly anomalous DIB intensities also tend to lie at high Galactic latitudes.