Decay of Solar Pores Driven by Small-scale Magnetic Reconnection Episodes

Abstract

We present the relationships between the disappearances of two small pores, magnetic cancellations, and magnetic reconnection episodes in the NOAA AR 12778 on 2020 October 26 with high-resolution observations of the New Vacuum Solar Telescope and the Solar Dynamics Observatory. Two emerging positive polarities (P1 and P2) approach a negative polarity (N1) with velocities of 0.26 and 0.42 km s−1, respectively. Then, two small-scale magnetic reconnection episodes occur between a series of magnetic loops that are rooted in these polarities. The reconnection inflow velocities are around 4.0 km s−1 which is faster than the movements of P1 and P2. Compared with the first magnetic reconnection episode, more magnetic free energy is released in the second reconnection episode due to the greater magnetic strength of P2. Subsequently, magnetic cancellation occurs first between P1 and N1, and then between P2 and N1. At the same time, the pores S1 (N1) and S2 (P2) decay and disappear. The area decay rate of the small pore S2 is estimated to be 7.3 Mm2 hr−1, which is larger than previously reported cases. And the flux decay rate of S2 is 5.1 × 1019 Mx hr−1, similar to the results obtained in the larger sunspots. We conclude that the magnetic reconnection episodes may be caused by both the movement of the magnetic polarities and the plasma dynamics themselves. The decay and disappearance of the small pores and the polarities are driven by magnetic reconnection episodes and then flux submergence. We suggest that a magnetic reconnection episode is a more efficient mechanism for the disappearance of solar pores.