A Patchy Cloud Model for the L to T Dwarf Transition
Date
2010-10-14
Authors
Marley, Mark S.
Saumon, Didier
Goldblatt, Colin
Journal Title
Journal ISSN
Volume Title
Publisher
IOP Publishing
Abstract
One mechanism suggested for the L to T dwarf spectral type transition is the appearance of relatively cloud-free regions across the disk of brown dwarfs as they cool. The existence of partly cloudy regions has been supported by evidence for variability in dwarfs in the late L to early T spectral range, but no self-consistent atmosphere models of such partly cloudy objects have yet been constructed. Here, we present a new approach for consistently modeling partly cloudy brown dwarfs and giant planets.We find that even a small fraction of cloud holes dramatically alter the atmospheric thermal profile, spectra, and photometric colors of a given object. With decreasing cloudiness objects briskly become bluer in J − K and brighten in J band, as is observed at the L/T transition. Model spectra of partly
cloudy objects are similar to our models with globally homogenous, but thinner, clouds. Hence, spectra alone may not be sufficient to distinguish partial cloudiness although variability and polarization measurements are potential observational signatures. Finally, we note that partial cloud cover may be an alternative explanation for the blue L dwarfs.
Description
Keywords
brown dwarfs-- stars, atmospheres
Citation
Marley, M.S., Saumon, D. & Goldblatt, C. 2010, "A Patchy Cloud Model for the L to T Dwarf Transition", The Astrophysical Journal Letters, vol. 723, no. 1, pp. L117-L121.