2003A&A...398..127S

We present the results of TNG near-IR low resolution spectroscopy of two (S7F5_254 and S7F5_45) sources belonging to a complete sample of 15 EROs with K'<18 and R-K'>5 selected from the MUNICS Survey. Both the spectra show a sharp drop in the continuum which can be ascribed only to the Balmer break. This places them at 1.2<z<1.5. Their rest-frame z=1.2 K-band absolute magnitude is M_K≃-26.6 (L∼7L^*). The comparison of the spectra and the photometric data with a grid of synthetic template spectra provides a redshift z≃1.22^–0.07_+0.2 for S7F5_254 and z≃1.46±0.02 for S7F5_45. The resulting lower limits to their stellar mass are M_stars^min=6x10¹¹M_☉ and M_stars^min=4x10¹¹M_☉. The minimum age of the last burst of star formation in S7F5_254 is 3.5Gyr while it is 0.5Gyr in S7F5_45 implying a minimum formation redshift z_f>3.5 and z_f>2 for the two EROs respectively.