2011MNRAS.418.1346L

We present the time series photometry of stars located in the extremely young open cluster Berkeley 59. Using the 1.04-m telescope at Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, we have identified 42 variables in a field of ∼13 {x} 13 arcmin² around the cluster. The probable members of the cluster have been identified using a (V, V-I) colour–magnitude diagram and a (J-H, H-K) colour–colour diagram. 31 variables have been found to be pre-main-sequence stars associated with the cluster. The ages and masses of the pre-main-sequence stars have been derived from the colour–magnitude diagram by fitting theoretical models to the observed data points. The ages of the majority of the probable pre-main-sequence variable candidates range from 1 to 5 Myr. The masses of these pre-main-sequence variable stars have been found to be in the range of ∼0.3 to ∼3.5 M_☉, and these could be T Tauri stars. The present statistics reveal that about 90 per cent T Tauri stars have period <15 d. The classical T Tauri stars are found to have a larger amplitude than the weak-line T Tauri stars. There is an indication that the amplitude decreases with an increase in mass, which could be due to the dispersal of the discs of relatively massive stars.