2010A&A...510L...8S

New near-infrared large-area sky surveys (e.g. UKIDSS, CFBDS, WISE) go deeper than 2MASS and aim at detecting brown dwarfs lurking in the solar neighbourhood that are even fainter than the latest known T-type objects, so-called Y dwarfs. Using UKIDSS data, we found a faint brown dwarf candidate with very red optical-to-near-infrared, but extremely blue near-infrared colours next to the recently discovered nearby L dwarf SDSS J141624.08+134826.7. We checked if the two objects are co-moving by studying their parallactic and proper motion and compared the new object with known T dwarfs. The astrometric measurements are consistent with a physical pair (sep≃75AU) at a distance d≃8pc. The extreme colour (J-K≃-1.7) and absolute magnitude (M_J=17.78±0.46 and M_K=19.45±0.52) make the new object appear as one of the coolest (T_eff≃600K) and nearest brown dwarfs, probably of late-T spectral type and possibly with a high surface gravity (logg≃5.0).