The present observational activity at the OAC appears to be strongly limited by the relatively low performance of the spectrograph, expecially as it concerns the spectropolarimetry where high S/N ratios and resolutions are necessary. After the previous changing, the spectrograph cannot be further improved and the acquisition of a new high efficiency spectrograph cannot be delayed.
With the scientific activity carried out at the OAC, the importance of a higher resolution is related to the spectropolarimetry with particular interest to the measure of stellar magnetic fields (Leone & Kurtz 2004); Doppler Imaging of active stars and binary systems; measuring starspots temperature from line depth ratios (Catalano et al. 2002); radial velocities (Catanzaro & Leto 2004), stellar atmosphere studies (i.e. determination of effective temperature, gravity, rotation velocity, micro macro-turbulence and abundances (Catanzaro, Leone & Leto 2004); modeling of Balmer lines in presence of expanding envelopes.
Moreover, it will be possible to carry out all those scientific programs that are usually based on R = 50000 spectrographs. As in the case of FEROS or ELODIE, with CAOS it will be possible to: Search for extra-solar planet systems; Asteroseismology, i.e. measurements of stellar oscillations; Long-term monitoring of hydrodynamic phenomena in hot stellar atmospheres by following the line-profile variations of photospheric and wind lines over their characteristic time scales from hours to months; Chromospheric variability by the simultaneous observation of the CaII H&K and H; Observations of diffuse insterstellar clouds in the interstellar medium which have a typical velocity seperation of 6 km s.