O2 signature in thin and thick O2-H2O ices⋆
Caselli, P.; Vasyunin, A. I.; Bizzocchi, L.; Giuliano, B. M.; Müller, B.
Germany, Russia, Latvia
Abstract
Aims: In this paper we investigate the detectability of the molecular oxygen in icy dust grain mantles towards astronomical objects.
Methods: We present a systematic set of experiments with O2-H2O ice mixtures designed to disentangle how the molecular ratio affects the O2 signature in the mid- and near-infrared spectral regions. All the experiments were conducted in a closed-cycle helium cryostat coupled to a Fourier transform infrared spectrometer. The ice mixtures comprise varying thicknesses from 8 × 10-3 to 3 μm. The absorption spectra of the O2-H2O mixtures are also compared to the one of pure water. In addition, the possibility to detect the O2 in icy bodies and in the interstellar medium is discussed.
Results: We are able to see the O2 feature at 1551 cm-1 even for the most diluted mixture of H2O:O2 = 9:1, comparable to a ratio of O2/H2O = 10% which has already been detected in situ in the coma of the comet 67P/Churyumov-Gerasimenko. We provide an estimate for the detection of O2 with the future mission of the James Webb Space Telescope (JWST).