New evidences for interstellar C 60 + ?

The discovery and synthesis of fullerenes led to the hypothesis that they may be present and stable in interstellar space. As first evidence for the largest molecule ever detected in space, we have recently detected two new diffuse interstellar bands (DIBs) in the near-infrared that are consistent with laboratory measurements of the C 60 cation. The inferred abundance (up to 0.9 % of cosmic carbon locked in C 60 +) suggested that fullerenes may play an important role in interstellar chemistry. We present new observations towards HD183143, HD37022 and HD 80077 at 9600Å from CFHT and ESO. The high quality of the spectra confirms without doubt the presence of the two DIBs at 9577 and 9632Å and allows to measure reliably their strength, width and band ratio. The two correlated DIBs decrease in a UV shielded cold cloud (HD80077) but increase in a region dominated by extreme UV radiation (HD37022), with a band ratio constant within errors. Both DIBs show the same width, also consistent with a common carrier. This width of 3 cm −1 is compatible with rotational contours of C 60 fullerene molecules. These results bring new evidences for C 60 + in addition to the match with laboratory spectra.