Photometry of Io and Europa at the Crimean Astrophysical Observatory and reasons for differences between ground-based and space observations

Abramenko, A. N.; Baida, G. V.; Zakrevskii, A. V.; Karachkina, L. G.; Prokof’eva-Mikhailovskaya, V. V.; Сергеева, Е. А.

doi:10.3103/s0190271711010013

Cited by 3 publications

(1 citation statement)

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“…An integration of the transverse magnetic field along a vast contour was applied. To derive the current densities in nodal points of a magnetogram, this method was applied for the first time by Abramenko and Gopasyuk (1987) and Abramenko, Gopasyuk and Ogir (1988).…”

Section: Local and Distributed Electric Currentsmentioning

confidence: 99%

Distributed Electric Currents in Solar Active Regions

2020

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Using magnetographic data provided by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, we analyzed the structure of magnetic fields and vertical electric currents in six active regions (ARs) with different level of flare activity. We found that electric currents are well balanced over the entire AR: for all of them the current imbalance is below 0.1%, which means that any current system is closed within an AR. Decomposition of the transverse magnetic field vector into two components allowed us to reveal the existence of large-scale vortex structures of the azimuthal magnetic field component around main sunspots of ARs. In each AR, we found a large-scale electric current system occupying a vast area of an AR, which we call distributed electric current. For ARs obeying the Hale polarity law and the hemispheric helicity sign rule, the distributed current is directed upward in the leading part of an AR and it appears to be closing back to the photosphere in the following part of an AR through the corona and chromosphere. Our analysis of the time variations of the magnitude of the distributed electric currents showed that lowflaring ARs exhibit small variations of the distributed currents in the range of ±20×10 12 A, whereas the highly flaring ARs exhibited significant slow variations of the distributed currents in the range of 30 − 95 × 10 12 A. Intervals of the enhanced flaring appear to be co-temporal with smooth enhancements of the distributed electric current.

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Section: Local and Distributed Electric Currentsmentioning

confidence: 99%