A search for variability in brown dwarfs and L dwarfs
C.A.L. Bailer-Jones and
Received 16 April 1999 / Accepted 15 June 1999
We have undertaken a differential photometric I band search for variability in three Pleiades brown dwarfs and three very low mass field L dwarfs. Analysis of the resultant time series for the Pleiades brown dwarfs (Teide 1, Calar 3, Roque 11) gives no evidence for variability (above 99% confidence) greater than 0.05 mags in any of these objects on timescales between 25 minutes and 27 hours. Time series of two of the L dwarfs, 2MASSW J0913032+184150 and 2MASSW J1146345+223053, are also consistent with no intrinsic variability (no significant variability above 0.07 mags for 30 mins 126 hours, and above 0.025 mags for 30 mins 75 hours, for the two objects respectively). However, the L dwarf 2MASSW J1145572+231730 shows evidence for variability of amplitude 0.04 magnitudes with a tentative period of about 7 hours. It is therefore interesting that Kirkpatrick et al. (1999) report an H emission line of 4.2 Å equivalent width for this star: If our detection is confirmed as a rotation period, it would support the link between rotation and H emission in very low mass stars.
Key words: methods: observational stars: activity stars: individual: 2MASSW J1145572+231730 stars: low-mass, brown dwarfs stars: rotation
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© European Southern Observatory (ESO) 1999
Online publication: August 13, 199