* Astronomy

Title: ULAS J141623.94 + 134836.3 - a faint common proper motion companion of a nearby L dwarf. Serendipitous discovery of a Y dwarf candidate in UKIDSS DR6
Authors: R.-D. Scholz

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 which are even fainter than the latest known T-type objects, so-called Y dwarfs. Using UKIDSS data, we have found a promising Y 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 check if the two objects are co-moving by studying their parallactic and proper motion and compare the Y dwarf candidate with known T dwarfs. The astrometric measurements are consistent with a physical pair (sep ~75 AU) at a distance d ~8 pc. The extreme colour (J-K ~-1.7) and absolute magnitude (M_K ~19.4) make the new object appear as the first representative of the new class of Y dwarfs.

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