NOAO >   Observing Info >   Approved Programs >   2013B-0288

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Proposal Information for 2013B-0288


PI: Esther Buenzli, University of Arizona, ebuenzli@email.arizona.edu
Address: Steward Observatory, 933 N Cherry Ave, Tucson, AZ 85721, USA

CoI: Daniel Apai, University of Arizona
CoI: Jacqueline Radigan, STScI
CoI: Neill Reid, STScI
CoI: Davin Flateau, University of Arizona

Title: Confirmation of probable high-amplitude variable brown dwarfs from an HST survey

Abstract: The spectral evolution of brown dwarfs is mainly driven by changes in temperature and cloud structure. Models predict that the drastic spectral changes between L and T dwarfs stem primarily from cloud dispersal, either through hole growth or thinning due to rain-out. Heterogeneous cloud cover results in flux variations as the brown dwarf rotates. Only three brown dwarfs with near-infrared variability amplitudes >1% are currently known. From a unique HST/WFC3 SNAP survey we identified three targets that show H band variability of \gtrsim0.5% already in 40 min. These sources have a large probability of being variable at the >1% percent level over a full rotation period of a few hours, doubling the known sample. We propose to confirm the variability of these targets with time-resolved SOAR/SPARTAN H-band photometry over one night (~ 7 h) per target to measure or constrain their variability amplitudes and rotation periods. They have different temperature and spectral subtypes than the already known variable brown dwarfs and will allow comparative studies of heterogeneous cloud structure in brown dwarfs across the L/T transition.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2013B-0288

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