Abstract
Since the hint of the existence of an invariable value of the vertical magnetic field (Bver) on umbra-penumbra boundaries in sunspots by Jurčák (2011), many investigations have focused on studying this property. Umbra-penumbra boundaries of stable sunspots are defined by a critical Bver (Jurčák et al. 2018, Schmassmann et al. 2018; Lindner et al. 2020).
On the other hand, when an umbra does not hold a sufficiently strong Bver, i.e. Bver is weaker than the critical value, penumbral magneto-convection overtakes (Jurčák et al. 2015; Jurčák et al. 2017).
Pores are a special type of spots formed by an umbra not surrounded by a penumbra. In this presentation we will talk about the similarities found between the boundary of pores and umbra-penumbra boundaries.
Moreover, we will discuss the role of Bver on the decay of pores and sunspots.