Definite spectroscopic evidence for magnetic reconnection in splitting of solar filament structure

Magnetic reconnection is a common course of that modifications magnetic topology and converts magnetic vitality to plasma kinetic vitality. Spatially resolved spectroscopic observations overlaying prolonged areas within the solar environment are uncommon, and thus the distribution and vitality partition of reconnection stay unclear.

A filament is a darker and denser construction within the solar atmosphere. Doppler shifts of bidirectional outflows, as particular proof for reconnection, haven’t been detected in solar filament splitting up to now.

Nevertheless, now, researchers led by Dr. Hu Huidong from the Nationwide Area Science Middle of the Chinese language Academy of Sciences, together with their collaborators from Max Planck Institute for Photo voltaic System Analysis in Germany and Nanjing College in China, have reported a magnetic-reconnection occasion that brought on the splitting of a solar filament construction, based mostly on spatially resolved spectroscopic information from the Interface Area Imaging Spectrograph (IRIS) and pictures from the Photo voltaic Dynamics Observatory (SDO).

The research was revealed in The Astrophysical Journal Letters.

“The filament construction was break up into two higher and decrease branches by magnetic reconnection, which ultimately erupted partially, with the higher department ejected and the decrease department retained,” stated Dr. Hu.

Neighboring giant blue- and redshifts (greater than 50 km/s) of the Si IV line within the brightening area between the 2 filament branches had been revealed, which spatially corresponded to giant nonthermal widths and enhanced intensities of the Si IV line. These are clear signatures of magnetic reconnection. The size of the reconnection area is unprecedentedly at least 14,000 km.

A double Gaussian match of the road spectra illustrated blue- and redshifts (as much as ~150 km/s) of the upward and downward outflows. The discount of the general line width indicated that the line-of-sight velocities decreased remarkably after the bidirectional outflows left the reconnection web site. Line broadening on the blue wing a number of arcseconds away from the reconnection web site was noticed, which could be indicative of turbulence that was induced when the upward outflow interacted with the higher filament department.

Differential-emission-measure evaluation confirmed that the temperature in the course of the reconnection was ~14 MK, ~9 MK greater than that earlier than the reconnection. The electron density was ~3.9×10¹⁰ cm^-3, about twice that earlier than the reconnection. The total thermal vitality was estimated to be ~1.3×10²⁷ ergs, which was a lot bigger than the kinetic energy.

“Our research has supplied particular spectroscopic proof for the splitting of a filament construction by magnetic reconnection,” stated Dr. Hu. “The reconnection is in an prolonged area with an unprecedented size, and the thermal vitality overwhelmingly dominates the kinetic vitality on this reconnection occasion.”