NOAO >   Observing Info >   Approved Programs >   2013B-0538

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Proposal Information for 2013B-0538


PI: Sandy Leggett, Gemini Observatory, sleggett@gemini.edu
Address: Gemini Observatory, 670 N. Aohoku Place, Hilo, HI 96720, USA

CoI: Mark Marley, NASA Ames
CoI: Didier Saumon, Los Alamos National Lab
CoI: Jonathan Fortney, UC Santa Cruz
CoI: Caroline Morley, UC Santa Cruz

Title: A Study of the 450K Transition from T to Y Dwarf, and of the 350K Y Dwarfs.

Abstract: We propose to use FLAMINGOS-2, GSAOI and NIRI to obtain Z/Y, J, H and K photometry, or a subset, for eight T9/9.5 dwarfs and five Y dwarfs. In parallel, we are expanding our models which include Cr, Cl and S clouds, to add H2O clouds. The T9/9.5 targets have been selected to study the transition from T to Y and appear to have a large range in J-H color. The scatter, if confirmed, probably reflects a range of cloud properties, and the T/Y transition is likely to be as complex as the L/T transition. Here, instead of a clearing of silicate clouds, the Cr, Cl and S clouds clear and H2O clouds form. Our models and the new data will enable investigation of the transition in terms of changes in temperature, gravity and cloudiness. The Y dwarf part of the project follows previous Gemini time, and essentially completes the near-IR photometric dataset for the known Y dwarfs. There are errors in earlier data, and our models together with reliable photometry can constrain temperature, gravity and cloudiness, and hence mass and age, for this 5 - 15 Jupiter-mass population of the solar neighborhood.


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