Formation of Compound Flux Rope by The Merging of Two Filament Channels, Associated Dynamics and its Stability

TL;DR

This study observes the formation of a compound flux rope through merging of two filament channels, analyzing associated plasma dynamics, stability, and magnetic properties, providing insights into flux rope formation and stability in the solar corona.

Contribution

It presents the first detailed observation of compound flux rope formation via merging of filaments, including plasma behavior, stability analysis, and magnetic field characteristics.

Findings

Filament merging leads to a stable compound flux rope.

Plasma heats up and moves along the flux rope during merging.

The flux rope remains stable within the corona, avoiding eruption.

Abstract

We present the observations of compound flux rope formation via merging of two nearby filament channels, associated dynamics and its stability that occurred on 2014 January 1 using multiwavelength data. We have also discussed the dynamics of cool and hot plasma moving along the newly formed compound flux rope. The merging started after the interaction between the southern leg of northward filament and the northern leg of the southward filament at around 01:21 UT and continue until a compound flux rope formed at around 01:33 UT. During the merging the cool filaments plasma heated up and started to move along the both side of the compound flux rope i.e., toward north (approx 265 km/s) and south (approx 118 km/s) from the point of merging. After travelling a distance of approx 150 Mm towards north the plasma become cool and started to returns back towards south ( approx 14 km/s) after 02:00 UT. The observations provide an clear example of compound flux rope formation via merging of two different flux ropes and occurrence of flare through tether cutting reconnection. However, the compound flux rope remained stable in the corona and made an confined eruption. The coronal magnetic field decay index measurements revealed that both the filaments and the compound flux rope axis lies within the stability domain (decay index less than 1.5), which may be the possible cause for their stability. The present study also deals with the relationship between the filaments chirality (sinistral) and the helicity (positive) of the surrounding flux rope.