Magnetic topology of a naked sunspot: Is it really naked?

TL;DR

This study investigates the magnetic topology of a naked sunspot, revealing that similar magnetic structures to regular sunspots can exist without a penumbra, explaining the presence of moving magnetic features.

Contribution

It demonstrates that a sunspot-like magnetic topology can be present in naked sunspots, challenging previous assumptions about their magnetic structure and MMF activity.

Findings

Naked sunspots can have magnetic structures similar to regular sunspots.

MMF activity can occur without a penumbra due to underlying magnetic topology.

Magnetic field topology explains MMF activity in naked sunspots.

Abstract

The high spatial, temporal and spectral resolution achieved by Hinode instruments give much better understanding of the behavior of some elusive solar features, such as pores and naked sunspots. Their fast evolution and, in some cases, their small sizes have made their study difficult. The moving magnetic features, despite being more dynamic structures, have been studied during the last 40 years. They have been always associated with sunspots, especially with the penumbra. However, a recent observation of a naked sunspot (one with no penumbra) has shown MMF activity. The authors of this reported observation expressed their reservations about the explanation given to the bipolar MMF activity as an extension of the penumbral filaments into the moat. How can this type of MMFs exist when a penumbra does not? In this paper, we study the full magnetic and (horizontal) velocity topology of the same naked sunspot, showing how the existence of a magnetic field topology similar to that observed in sunspots can explain these MMFs, even when the intensity map of the naked sunspot does not show a penumbra.