S18A0027abst
S18A0027
The discovery of C60 in the laboratory (Kroto et al. 1985) three decades ago triggered an intensive search of fullerenes in astrophysical environments. C60 has been claimed in a wealth of astronomical sources (e.g. Brieva et al. 2016), and its ionised form C60+ is assigned as the carrier of two diffuse interstellar bands (DIBs) at 9577 A and 9632 A (Campbell et al. 2015). Two recent studies have, however, challenged the claim that fullerenes are abundant in the ISM (Brieva et al. 2016, Galazitdinov et al. 2017). Here we focus on the assignment of C60+ as the carrier of DIBs. Galazutdinov et al. (2017) who concluded that the ratio between the 9577 A and 9632 A absorption lines is variable, which is not expected if they result from C60+. We find that their spectra are of insufficent signal to noise ratio, insufficient spectral resolution, and an incomplete treatment of the telluric absorption lines, to draw such far-fetching conclusions. Our aim is to use the HDS to accurately determine the strength of five C60+ absorption lines in the optical spectrum toward Cyg OB2. The exact wavelengths and their relative intensity ratios will allow us to firmly establish whether or not C60+ is present in the diffuse ISM.
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