Astronomy and Astrophysics – Astrophysics
Scientific paper
2003-04-04
Astronomy and Astrophysics
Astrophysics
22 pages, 8 figures, Solar Physics (in press)
Scientific paper
In order to understand whether major flares or coronal mass ejections (CMEs) can be related to changes in the longitudinal photospheric magnetic field, we study 4 young active regions during seven days of their disc passage. This time period precludes any biases which may be introduced in studies that look at the field evolution during the short-term flare or CME period only. Data from the Michelson Doppler Imager (MDI) with a time cadence of 96 minutes are used. Corrections are made to the data to account for area foreshortening and angle between line of sight and field direction, and also the underestimation of the flux densities. We make a systematic study of the evolution of the longitudinal magnetic field, and analyze flare and CME occurrence in the magnetic evolution. We find that the majority of CMEs and flares occur during or after new flux emergence. The flux in all four active regions is observed to have deviations from polarity balance both on the long-term (solar rotation) and on the short term (few hours). The long-term imbalance is not due to linkage outside the active region; it is primarily related to the east-west distance from central meridian, with the sign of polarity closer to the limb dominating. The sequence of short term imbalances are not closely linked to CMEs and flares and no permanent imbalance remains after them. We propose that both kinds of imbalance are due to the presence of a horizontal field component (parallel to the photospheric surface) in the emerging flux.
Démoulin Pascal
Green Lucie M.
Mandrini Cristina Hemilse
van Driel-Gesztelyi Lidia
No associations
LandOfFree
How are Emerging Flux, Flares and CMEs Related to Magnetic Polarity Imbalance in MDI Data? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with How are Emerging Flux, Flares and CMEs Related to Magnetic Polarity Imbalance in MDI Data?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and How are Emerging Flux, Flares and CMEs Related to Magnetic Polarity Imbalance in MDI Data? will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-385038