GTC OSIRIS z-band imaging of Y dwarfs

Lodieu, N.; Béjar, V. J. S.; Rebolo, R.
Bibliographical reference

Astronomy and Astrophysics, Volume 550, id.L2, 4 pp.

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2
2013
Number of authors
3
IAC number of authors
3
Citations
16
Refereed citations
16
Description
Aims: 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. Methods: 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). Results: 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 turnover towards bluer colours may be a consequence of the presence of sulfide clouds with different thicknesses, the depletion of alcalines, and/or gravity effects.
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