The Metallicity of Palomar 1

Palomar 1 is a peculiar Galactic globular cluster suspected of being younger than the bulk of Galactic halo objects. However, such a low age can be confirmed only after a reliable determination of the metallicity. In the present paper, we use the equivalent widths, W, of the Ca II triplet on medium-resolution spectra to determine the metal content of Pal 1. From the comparison of the luminosity-corrected W's in four stars of Pal 1 with those of a sample of stars in each of three calibration clusters (M2, M15, and M71), we derive [Fe/H] = -0.6 ± 0.2 on the Zinn-West scale or [Fe/H] = -0.7 ± 0.2 on the Carretta-Gratton scale. We also obtain a radial velocity vr = -82.8 ± 3.3 km s-1 for Pal 1.