We present a high signal to noise ( S/N > 10 ) medium resolution ( R=2000 ) LBT-LUCIFER spectrum of the early-type galaxy ( ETG ) S2F1-142 at z \simeq 1.4 .
By means of the CaT line at 8662 Å , we measured its redshift z = 1.386 \pm 0.001 and we estimated its velocity dispersion \sigma _ { v } = 340 ^ { -60 } _ { +120 } km/s .
Its corresponding virial mass is 3.9 \times 10 ^ { 11 } M _ { \odot } , compatible with the stellar mass estimates obtained assuming Initial Mass Functions ( IMFs ) less dwarf rich than the Salpeter one .
S2F1-142 is a compact galaxy with R _ { e } =3.1 \pm 0.2 kpc , i.e. , an effective radius more than three times smaller than the average R _ { e } of early-type galaxies with the same mass in the local universe .
At the same time , we found local and high redshift galaxies with a similar mass content and similar effective radius confirming that it is fully consistent with the already available measures of R _ { e } and \sigma _ { v } both in the local and in the distant universe .
Considering the distribution of R _ { e } and \sigma _ { v } as a function of the stellar mass content of ETGs , both in the local and in the distant universe , we noticed that the measured velocity dispersions of the more compact galaxies are on average slightly lower than expected on the basis of their compactness and the virial theorem , suggesting that i ) their dark matter content is lower than in the more diffuse galaxies and/or ii ) their luminosity profiles are steeper than in the more diffuse galaxies and/or iii ) their larger compactness is an apparent effect caused by the overestimate of their stellar mass content ( due to bottom lighter IMF and/or systematic affecting the stellar mass estimates ) .