a) Angular extension of the flux rope as a function of the radial distance of the top of the flux rope for all the simulations that show a CME. Simulations are grouped according to the simulation parameter T given with different colours. b) Map of B_θ/|B | in the (r−φ) plane passing through the centre of the bipoles at t = 1.55 h for the simulation with T = 3 MK and B_max = 21 G. The map shows the full domain of our simulations from r = 1 R_⊙ to r = 4 R_⊙.