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ESP Online Seminar: Interactions between pre-existing and emerging magnetic flux systems observed with IRIS (S. Guglielmino)

  • Date: May 3, 2018
  • Time: 11:00 - 12:00
  • Speaker: Salvo Guglielmino
  • Osservatorio Astrofisico di Catania
  • Location: Osservatorio Astrofisico di Catania (broadcasted at MPS)
  • Room: Auditorium
  • Host: Andreas Lagg
We report multi-wavelength ultraviolet observations taken with the IRIS satellite, concerning the emergence phase in the upper chromosphere and transition region of an emerging flux region (EFR) embedded in the unipolar plage of active region NOAA 12529. IRIS data are complemented by full-disk, simultaneous observations of the Solar Dynamics Observatory satellite, relevant to the photosphere and the corona. The photospheric configuration of the EFR is also analysed by measurements taken with the spectropolarimeter onboard the Hinode satellite, when the EFR was fully developed. Recurrent intense brightenings that resemble UV bursts, with counterparts in all coronal passbands, are identified at the edges of the EFR. Jet activity is also found at chromospheric and coronal levels, near the observed brightness enhancement sites. Analysis of the IRIS line profiles reveals heating of dense plasma in the low solar atmosphere and the driving of bi-directional, high-velocity flows with speeds up to 100 km/s at the same locations. Comparing these signatures with previous observations and numerical models, we suggest evidence of several long-lasting, small-scale magnetic reconnection episodes between the emerging bipole and the ambient field. This process leads to the cancellation of a pre-existing photospheric flux concentration of the plage with the opposite polarity flux patch of the EFR. Moreover, the reconnection appears to occur higher in the atmosphere than usually found in UV bursts, explaining the observed coronal counterparts.


We report multi-wavelength ultraviolet observations taken with the IRIS


satellite, concerning the emergence phase in the upper chromosphere and


transition region of an emerging flux region (EFR) embedded in the


unipolar plage of active region NOAA 12529. IRIS data are complemented


by full-disk, simultaneous observations of the Solar Dynamics


Observatory satellite, relevant to the photosphere and the corona. The


photospheric configuration of the EFR is also analysed by measurements


taken with the spectropolarimeter onboard the Hinode satellite, when the


EFR was fully developed. Recurrent intense brightenings that resemble UV


bursts, with counterparts in all coronal passbands, are identified at


the edges of the EFR. Jet activity is also found at chromospheric and


coronal levels, near the observed brightness enhancement sites. Analysis


of the IRIS line profiles reveals heating of dense plasma in the low


solar atmosphere and the driving of bi-directional, high-velocity flows


with speeds up to 100 km/s at the same locations. Comparing these


signatures with previous observations and numerical models, we suggest


evidence of several long-lasting, small-scale magnetic reconnection


episodes between the emerging bipole and the ambient field. This process


leads to the cancellation of a pre-existing photospheric flux


concentration of the plage with the opposite polarity flux patch of the


EFR. Moreover, the reconnection appears to occur higher in the


atmosphere than usually found in UV bursts, explaining the observed


coronal counterparts.

 
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