Observational Evidence of Optical Variability in L Dwarfs

Abstract

The results of quasi-simultaneous continuous monitoring of six L dwarfs in the R and I bands are presented. A careful analysis of the data shows that the object 2MASSW J0036+1821 is variable in the I and R bands. The amplitudes of our variable object were found to be 0.010 in the I band and 0.030 in the R band. Interestingly, while 2MASSW J0036+1821 was variable in the I band, it remained nonvariable in the R band, and vice versa. As most of the previous variability search programs of L dwarfs were carried out in the I band, this is the first evidence of this type of strange phenomena. The time evolution and rapid formation of dust on a macroscopic scale can plausibly produce this type of nonperiodic random variability.