Initial parameter space for producing SNe Ia: the initial orbital period (P _orb,i )—initial red giant donor mass (M _RG,i ) plane for WD+RG systems. The initial WD masses are 1.0 and 1.2 M _⊙. The panels show the results for WDs with no or intermediate-strength magnetic fields (upper panel), and high magnetic fields (lower panel), respectively. Blue stars show the cases that produce SNe Ia. The solid blue lines show the parameter regions within which SNe Ia are produced. The cyan triangles in the upper regions in the figure indicate the occurrence of a common envelope, and the black crosses in the lower regions show where nova outbursts occur. The red triangles and black squares on the sides show regions with inefficient mass transfer.