Probing Dust around Brown Dwarfs: The naked LP 944-20 and the Disk of   Cha Ha2
  We present the first mid-infrared (MIR) detection of a field brown dwarf (BD) and the first ground-based MIR measurements of a disk around a young BD candidate. We prove the absence of warm dust surrounding the field BD LP 944-20. In the case of the young BD candidate Cha Ha2, we find clear evidence for thermal dust emission from a disk. Surprisingly, the object does not exhibit any silicate feature as previously predicted. We show that the flat spectrum can be explained by an optically thick flat dust disk. 
D. Apai, I. Pascucci, Th. Henning, M. F. Sterzik, R. Klein, D.   Semenov, E. Guenther, B. Stecklum