BETTONI, DanielaDanielaBETTONIFALOMO, RenatoRenatoFALOMOScarpa, RiccardoRiccardoScarpaNegrello, MattiaMattiaNegrelloOmizzolo, AlessandoAlessandoOmizzoloCorradi, Romano L. M.Romano L. M.CorradiReverte, DanielDanielReverteVulcani, BenedettaBenedettaVulcani2020-12-152020-12-1520192041-8205http://hdl.handle.net/20.500.12386/28859We report the study of an “Einstein Cross” configuration first identified in a set of HST images by Cerny et al. Deep spectroscopic observations obtained at the Spanish 10.4 m Gran Telescopio Canarias telescope, allowed us to demonstrate the lens nature of the system, that consists of a Lyman-break galaxy (LBG), not a quasi-stellar object as is usually the case, at z = 3.03 lensed by a galaxy at z = 0.556. Combining the new spectroscopy with the archival HST data, it turns out that the lens is an elliptical galaxy with M <SUB> V </SUB> = -21.0, effective radius 2.8 kpc, and stellar velocity dispersion σ = 208 ± 39 km s<SUP>-1</SUP>. The source is an LBG with Lyα luminosity ∼L* at that redshift. From the modeling of the system, performed by assuming a singular isothermal ellipsoid (SIE) with external shear, we estimate that the flux source is magnified about 4.5 times, and the velocity dispersion of the lens is {σ }<SUB>SIE</SUB>}={197.9}<SUB>-1.3</SUB><SUP>+2.6</SUP> km s<SUP>-1</SUP>, in good agreement with the value derived spectroscopically. This is the second case known of an Einstein cross of an LBG.STAMPAenArticle10.3847/2041-8213/ab0aeb2-s2.0-85063483275000460971600002https://iopscience.iop.org/article/10.3847/2041-8213/ab0aeb/pdf2019ApJ...873L..14BFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation