The maximum magnetic flux in an active region

The Photometric-Magnetic Dynamical model handles the evolution of an individual sunspot as an autonomous nonlinear, though integrable, dynamical system. The model considers the simultaneous interplay of two different interacted factors: The photometric and magnetic factors, respectively, characterizing the evolution of the sunspot visible area A on the photosphere, and the simultaneous evolution of the sunspot magnetic field strength B. All the possible sunspots are gathered in a specific region of the phase space (A, B). The separatrix of this phase space region determines the upper limit of the values of sunspot area and magnetic strength. Consequently, an upper limit of the magnetic flux in an active region is also determined, found to be ≈7.23 × 10²³ Mx. This value is phenomenologically equal to the magnetic flux concentrated in the totality of the granules of the quite Sun. Hence, the magnetic flux concentrated in an active region cannot exceed the one concentrated in the whole photosphere.