Multi-wavelength ultraviolet (UV) observations by the IRIS satellite in active region NOAA 12529 have recently pointed out the presence of long-lasting brightenings, akin to UV bursts, and simultaneous plasma ejections occurring in the upper chromosphere and transition region during secondary flux emergence. These signatures have been interpreted as evidence of small-scale, recurrent magnetic reconnection episodes between the emerging flux region (EFR) and the pre-existing plage field. Here, we characterize the UV emission of these strong, intermittent brightenings and we study the surge activity above the chromospheric arch filament system (AFS) overlying the EFR. We analyze the surges and the cospatial brightenings observed at different wavelengths. We find an asymmetry in the emission between the blue and red wings of the Si IV 1402 ̊A and Mg II k 2796.3 ̊A lines, which clearly outlines the dynamics of the structures above the AFS that form during the small-scale eruptive phenomena. We also detect a correlation between the Doppler velocity and skewness of the Si IV 1394 ̊A and 1402 ̊A line profiles in the UV burst pixels. Finally, we show that genuine emission in the Fe XII 1349.4 ̊A line is cospatial to the Si IV brightenings. This definitely reveals a pure coronal counterpart to the reconnection event.

IRIS Observations of Magnetic Interactions in the Solar Atmosphere between Preexisting and Emerging Magnetic Fields. II. UV Emission Properties

Guglielmino S. L.
Investigation
;
Zuccarello F.
Investigation
2019-01-01

Abstract

Multi-wavelength ultraviolet (UV) observations by the IRIS satellite in active region NOAA 12529 have recently pointed out the presence of long-lasting brightenings, akin to UV bursts, and simultaneous plasma ejections occurring in the upper chromosphere and transition region during secondary flux emergence. These signatures have been interpreted as evidence of small-scale, recurrent magnetic reconnection episodes between the emerging flux region (EFR) and the pre-existing plage field. Here, we characterize the UV emission of these strong, intermittent brightenings and we study the surge activity above the chromospheric arch filament system (AFS) overlying the EFR. We analyze the surges and the cospatial brightenings observed at different wavelengths. We find an asymmetry in the emission between the blue and red wings of the Si IV 1402 ̊A and Mg II k 2796.3 ̊A lines, which clearly outlines the dynamics of the structures above the AFS that form during the small-scale eruptive phenomena. We also detect a correlation between the Doppler velocity and skewness of the Si IV 1394 ̊A and 1402 ̊A line profiles in the UV burst pixels. Finally, we show that genuine emission in the Fe XII 1349.4 ̊A line is cospatial to the Si IV brightenings. This definitely reveals a pure coronal counterpart to the reconnection event.
2019
Sun: chromosphere — Sun: transition region — Sun: UV radiation — Sun: magnetic fields — magnetic reconnection
File in questo prodotto:
File Dimensione Formato  
IRIS Observations of Magnetic Interactions in the Solar Atmosphere.pdf

accesso aperto

Tipologia: Versione Editoriale (PDF)
Dimensione 4.96 MB
Formato Adobe PDF
4.96 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/358903
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 20
  • ???jsp.display-item.citation.isi??? 19
social impact