Earth's collision with a solar filament on 21 January 2005: Overview

Abstract

, one of the fastest interplanetary coronal mass ejections (ICME) of solar cycle 23, containing exceptionally dense plasma directly behind the sheath, hit the magnetosphere. We show from charge-state analysis that this material was a piece of the erupting solar filament and further, based on comparisons to the simulation of a fast CME, that the unusual location of the filament material was a consequence of three processes. As the ICME decelerated, the momentum of the dense filament material caused it to push through the flux rope toward the nose. Diverging nonradial flows in front of the filament moved magnetic flux to the sides of the ICME. At the same time, reconnection between the leading edge of the ICME and the sheath magnetic fields worked to peel away the outer layers of the flux rope creating a remnant flux rope and a trailing region of newly opened magnetic field lines. These processes combined to move the filament material into direct contact with the ICME sheath region. Within 1 h after impact and under northward interplanetary magnetic field (IMF) conditions, a cold dense plasma sheet formed within the magnetosphere from the filament material. Dense plasma sheet material continued to move through the magnetosphere for more than 6 h as the filament passed by the Earth. Densities were high enough to produce strong diamagnetic stretching of the magnetotail despite the northward IMF conditions and low levels of magnetic activity. The disruptions from the filament collision are linked to an array of unusual features throughout the magnetosphere, ionosphere, and atmosphere. These results raise questions about whether rare collisions with solar filaments may, under the right conditions, be a factor in producing even more extreme events.

Redefining the Boundaries of Interplanetary Coronal Mass Ejections From Observations at the Ecliptic Plane

“…Indeed, the helium density exceeds by 10 % the proton number density, consistent with the photospheric abundance of He 2+ . Considering the similarity of these features with those described by Burlaga et al (1998) and Kozyra et al (2013), we suggest that this high-density region at the rear of the magnetic cloud might be filament material.…”

Geomagnetic storms: historical perspective to modern view

“…What could this "plasma plug" be? Kozyra et al (2013) have found that high plasma density solar filaments (the most sunward part of CMEs) play prominent roles in extreme ICME events. Perhaps with more detailed research and simulations we will eventually know the answer of whether this hypothesis or another one can explain the 1859 storm in detail.…”

The Physical Processes of CME/ICME Evolution

“…Such events remain rare compared to the observed fraction of CMEs associated with prominence eruptions. A possible example is the 21 January 2005 ICME event, where both charge state analysis and simulation (Kozyra et al 2013;Manchester et al 2014b) strongly suggest that cold dense prominence material associated with a fast CME impacted the Earth.…”