2002MNRAS.333L..16S

We present near-infrared spectroscopy and Hubble Space Telescope (HST) imaging of galaxy J003707+0909.5, the brightest of three gravitationally lensed images of an extremely red object (ERO) at z =1.6, in the field of the massive cluster A68 (z =0.255). We exploit the superlative resolution of our HST data and the enhanced spatial resolution and sensitivity afforded by the lens amplification to reconstruct the source-plane properties of this ERO. Our morphological and photometric analysis reveals that EROJ003707 is an L^{starf} early-type disc galaxy and we estimate that ∼10 per cent of galaxies with (R-K)≥5.3 and K ≤21 may have similar properties. The unique association of passive EROs with elliptical galaxies therefore appears to be too simplistic. We speculate on the evolution of EROJ003707: if gas continues to cool on to this galaxy in the manner predicted by hierarchical galaxy formation models, then by the present day, EROJ003707 could evolve into a very luminous spiral galaxy.