Lifetime of Sunspots and Pores

Abstract

The lifetime of individual sunspots and pores is analyzed according to Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) data from the period 2010 – 2022. It is found that the lifetime of individual sunspots and pores differs from the Gnevyshev–Waldmeier rule formulated for groups of sunspots. The dependence of the lifetime has a different pattern for different types of spots. For pores, the lifetime does not depend on the polarity of the magnetic field and has a logarithmic dependence on the area $T_{\mathrm{pr}}=0.24(\pm 0.01)+0.55(\pm 0.14) {\mathrm{log}}(S_{\mathrm{mx}})$. For regular sunspots with a developed penumbra, the dependence on the area has a linear form, but depends on the polarity of the magnetic field. For sunspots with a magnetic field of the leading polarity $T^{\mathrm{sp}}_{\mathrm{ld}} =-0.62 (\pm 0.2)+0.036 (\pm 0.002) S_{\mathrm{mx}}$. For sunspots of trailing polarity $T^{\mathrm{sp}}_{\mathrm{tr}} =0.95 (\pm 0.1)+0.01 (\pm 0.001) S_{\mathrm{mx}}$. The decay time and the total lifetime of sunspots is related to the rate of flow in sunspots. The average vertical speed in sunspots decreases with their increasing area. Moreover, the flow rate in the sunspots of the trailing polarity is higher than in the sunspots of the leading polarity. This difference in the velocity explains the difference in the lifetime of the sunspots of the leading and trailing magnetic polarity.