GTC OSIRIS z-band imaging of Y dwarfs

Abstract

The aim of the project is to contribute to the characterisation of the spectral energy distribution of the coolest brown dwarfs discovered to date, the Y dwarfs. We obtained z-band far-red imaging for six Y dwarfs and a T9+Y0 binary with the OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) instrument on the 10.4-m Gran Telescopio de Canarias (GTC). We detect five of the seven known Y dwarfs in the $z$-band, infer their optical-to-infrared colours, and measure their proper motions. We find a higher dispersion in the z-J and z-H colours of Y0 dwarfs than in T dwarfs. This dispersion is found to be correlated with H-w2. The high dispersion in the optical-to-infrared colours of Y dwarfs and the possible turn-over towards bluer colours may be a consequence of the presence of sulfide clouds with different thicknesses, the depletion of alcalines, and/or gravity effects.

5 pages, 4 figures, 1 tables, accepted as A&A letter

References in corpus (9)

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• CFBDS J005910.90-011401.3: reaching the T-Y Brown Dwarf transition?
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• Hubble Space Telescope Spectroscopy of Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer
• The AllWISE Motion Survey, Part 2
• A Uniform Retrieval Analysis of Ultracool Dwarfs. III. Properties of Y-Dwarfs
• Three New Cool Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer (WISE) and an Improved Spectrum of the Y0 Dwarf WISE J041022.71+150248.4
• The Spectral Energy Distribution of the Coldest Known Brown Dwarf
• Discovery of a Low-Luminosity, Tight Substellar Binary at the T/Y Transition
• Discovery of a new Y dwarf: WISE J030449.03-270508.3
• The Collapse of the Wien Tail in the Coldest Brown Dwarf? Hubble Space Telescope Near-Infrared Photometry of WISE J085510.83-071442.5
• An Improved Near-Infrared Spectrum of the Archetype Y Dwarf WISEP J182831.08+265037.8
• WEIRD: Wide-orbit Exoplanet search with InfraRed Direct imaging
• Near-infrared Detection of WD 0806-661 B with the Hubble Space Telescope
• Parallaxes and Infrared Photometry of three Y0 dwarfs
• Optical Properties of Metal-poor T Dwarf Candidates
• Optical constraints on the coldest metal-poor population