XMMU J100750.5+125818: a strong lensing cluster at z=1.082

We report on the discovery of the X-ray luminous cluster XMMU J100750.5+125818 at redshift 1.082 based on 19 spectroscopic members. The cluster displays several strong lensing features. SED modeling of the lensed arc features from multicolor imaging with the VLT and the LBT reveals likely redshifts similar to 2.7 for the most prominent of the lensed background galaxies. Mass estimates are derived for different radii from the velocity dispersion of the cluster members, M-200 similar or equal to 1.8 x 10(14) M-circle dot, from the X-ray spectral parameters, M-500 similar or equal to 1.0 x 10(14) M-circle dot, and the largest lensing arc, M-SL similar or equal to 2.3 x 10(13) M-circle dot. The projected spatial distribution of cluster galaxies appears to be elongated, and the brightest galaxy lies off center with respect to the X-ray emission, indicating a not yet relaxed structure. XMMU J100750.5+125818 offers excellent diagnostics of the inner mass distribution of a distant cluster with strong and weak lensing, in combination with optical and X-ray spectroscopy.