LESIA - Observatoire de Paris

Precursors of Magnetic Flux Emergence in the Moat Flows of Active Region AR12673

mercredi 3 octobre 2018

Mercredi 24 octobre 2018 à 11h00 , Lieu : Salle de conférence du bâtiment 17

I will describe observations of magnetic disturbances in active region AR12673 between 1 and 3 September 2017 seen as a disruption of the moat flow several hours before the onset of strong flux emergence near the main sunspot. The moat flow is commonly known as a radially oriented strong outflow of photospheric plasma surrounding sunspots, which ends abruptly and shapes an annular pattern around the penumbra. Using highly accurate methods of tracking this photospheric flow applied to SDO/HMI data, we are able to describe the evolution of the moat surrounding the main sunspot of AR 12673. We find that several hours before the emergence of strong magnetic flux near the main sunspot, the moat boundaries are broken at these very same locations. This behavior is observed both on 1 and 3 September. There is no such behavior observed in the absence of flux emergence. These observational results pose the question of how often they occur in other active regions and whether the disruption of the moat flow might be, like in this case, an indication of impending enhanced magnetic activity or simply a coincidental event. I will also describe ongoing work using my new photospheric tracking framework adapted specifically for HMI and that enables systematic analyses of the moat flows as well as the relationship between supergranular flows and the magnetic evolution in emerging active regions.