Solar system

Searching for water in the asteroid belt.

The hydroxide (OH) emission at 308 nm in the near-UV is one of the strongest signature to search for water in our solar system, and represents the most compelling next step to confirm the presence of water ice in main belt comets. Detecting water outgassing in the asteroid belt would point to a potentially large population of icy bodies, hence a large reservoir of water, of considerable interest in the context of models of the formation and evolution of the inner solar system . However, this would only be possible with a near-UV spectrograph significantly more sensitive than currently the available facilities.

Measuring the N2/CO ratio in comets.

The N2/CO ratio in cometary ices is very sensitive to the formation temperature of comets and measuring this ratio is important to decipher models of planetesimal formation and constrain the physical properties of the solar nebula at the time of comet formation. This ratio is very difficult to measure using ground-based observations but it can be estimated using near-UV observations of several N2+ and CO+ emission bands in the coma of comets. This requires a high sensitivity and spectral resolution in the near-UV.

Fig.1 X-shooter spectrum of main belt comet P/2012 T1 (black) with spectrum of a more active Jupiter family comet (9P/Tempel 1) overlaid in blue, showing the expected wavelengths of emission features from comet gas. Significantly better S/N in the UV is needed to search for very weak outgassing of OH by main belt comets (Snodgrass et al. 2017b).