The stellar population of the Small Magellanic Cloud near NGC 121. I - The mean metallicity, metallicity spread, and radial velocity of SMC halo giants

Technological advances make it now possible to conduct CCD photometry studies of stars in the halo of the Magellanic Clouds, taking into account the age and chemical composition of the oldest stars, the star-formation rate, and the age-metallicity relations. Recent reserch demonstrates that these relationships are different in the Clouds and in the Galaxy. The present paper is concerned with an examination of the giant stars of the SMC halo in the vicinity of the SMC cluster NGC 121, giving attention to the chemical composition and radial velocity of these objects. Astrometry and photometry based on direct photographs are considered along with spectroscopic observations, taking into account reduction techniques, sample spectra, radial velocities, and spectrophotometric indices and metallicity spread of giants.