Time resolved spectroscopy of the variable brown dwarf Kelu - 1 ⋆

We report the results of observations designed to investigate the spectroscopic signatures of dust clouds on the L2 brown dwarf Kelu-1. Time resolved medium resolution spectra show no significant evidence of variability in the dust sensitive TiO, CrH and FeH bandheads on the timescale of 1–24 hours. We do however report periodic variability in the psuedo-equivelent width of Hα consistent with the 1.8 hour rotation period previously reported for this object (Clarke, Tinney & Covey 2002). Near-contemporaneous I-band photometry shows evidence for non-periodic variability at the level of 2%.