Kinematic and Energetic Properties of the 2012 March 12 Polar Coronal Mass Ejection

TL;DR

This study analyzes the energetics and properties of the 2012 polar CME, revealing similarities with low-latitude CMEs and supporting the idea that all CMEs originate from magnetically closed regions regardless of their solar location.

Contribution

It provides the first detailed energetic analysis of a polar CME, showing its similarities to low-latitude CMEs and supporting a unified magnetic origin model.

Findings

CME mass and kinetic energy are typical of low-latitude CMEs.

Approximately 19% of the source region's free energy powers the CME.

Thermal energy in the PEA is a small fraction of the CME kinetic energy.

Abstract

We report on the energetics of the 2012 March 12 polar coronal mass ejection (CME) originating from a southern latitude of ~60o. The polar CME is similar to low-latitude CMEs in almost all respects: three-part morphology, post eruption arcade (PEA), CME and filament kinematics, CME mass and kinetic energy, and the relative thermal energy content of the PEA. From polarized brightness images, we estimate the CME mass, which is close to the average mass of low-latitude CMEs. The CME kinetic energy (3.3x1030 erg) is also typical of the general population of CMEs. From photospheric magnetograms, we estimate the free energy (1.8x1031 erg) in the polar crown source region, which we find is sufficient to power the CME and the PEA. About 19% of the free energy went into the CME kinetic energy. We compute the thermal energy content of the PEA (2.3x1029 erg) and find it to be a small fraction (6.8%) of the CME kinetic energy. This fraction is remarkably similar to that in active region CMEs associated with major flares. We also show that the 2012 March 12 is one among scores of polar CMEs observed during the maximum phase of cycle 24. The cycle 24 polar crown prominence eruptions have the same rate of association with CMEs as those from low-latitudes. This investigation supports the view that all CMEs are magnetically propelled from closed field regions, irrespective of their location on the Sun (polar crown filament regions, quiescent filament regions or active regions).