NGTS Variability Study

We utilise a generalisation of the autocorrelation function(the G-ACF), which applies to irregularly sampled time series data. We extract variability periods for 16,880stars from late-A through to mid-M spectral types and periods between 0.1 and 130 days with no assumed variability model.

We find variable signals associated with a number of astrophysical phenomena, including stellar rotation, pulsations and multiple-star systems. The extracted variability periods are compared with stellar parameters taken from Gaia DR2, which allows us to identify distinct regions of variability in the Hertzsprung-Russell Diagram. We explore a sample of rotational main-sequence objects in period-colour space, in which we observe a dearth of rotation periods between 15 and 25 days.