The Unusual Event of October 26, 2010: An “Almost” Coronal Hole

Abstract:

Coronal holes are dark regions in the solar corona that develop where open magnetic field lines are found. They come in many different shapes, sizes, and forms. Ephemeral coronal holes are a short-lived form of the phenomena, sometimes lasting only a few rotations. On October 26, 2010, NASA’s Solar Dynamics Observatory (SDO) observed what was first thought to be an unusual ephemeral coronal hole, appearing for less than 48 hours and surrounded by a filament. We present an analysis of the area and magnetic signatures of the filament and suspected hole, as well as solar wind data. Multiple EUV channels from SDO/AIA are combined with magnetograms from SDO/HMI and the GONG network to quantify the evolution of this event. Another ephemeral coronal hole from June 2015 is used a comparison. Results from this analysis show that the 2010 event was not an ephemeral coronal hole, but rather a solar ‘hiccup’ – the attempted, and failed, formation of a small coronal hole. While the reasons behind the failure remain speculative, these findings show that a lot of potential lies in future research of this event – in observing the interactions between the hole and the filament, and our continued understanding of the formation and characteristics of coronal holes.