The photometric estimate of the metallicity and the age of the Azzopardi et al. (1991, A&AS 88, 265) carbon stars (Ng 1997, A&A 328, 211) is revised to respectively Z~0.004 and ~0.1 Gyr. Under the hypothesis that the carbon stars are located at a distance related to the Sagittarius dwarf galaxy, the broad velocity dispersion of the stars can only be explained if they were formed out of Galactic material during a recent crossing of the Sagittarius dwarf galaxy through the Galactic plane.
Comment: 7 pages LaTeX, 4 figures, accepted for publication in A&A Main Journal