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A Statistical Study on the Relationship between the Transport Rate of Magnetic Helicity and Solar Flares  

Yin Zhang   Submitted: 2009-09-06 21:18

We present in this paper a statistical study of which is aimed at understanding the fact that some flares (type I flare) are associated with sharp variations of the transport rate of the magnetic helicity (dH/dt) and others not (type II flare). The sample consists of 49 M-class and X-class flares which produced by 9 isolated active regions. Used high temporal magnetograms obtained by the Michelson Doppler Imager (MDI) instrument on the Solar and Heliospheric Observatory (SOHO), we calculate the temporal variation of dH/dt during the flaring time, and compare its profile with the soft X-ray flux. We find that type I flares have longer duration and higher peak flux in soft X-ray than type II flares. Furthermore, the ratio of total unsigned magnetic flux of the host active region to that of the visible solar disk is also higher for type I flares, while the total flux itself is independent of the flare type. Our results show that whether the flare is associated with sharp variations of dH/dt depends on the properties of the flare and of its host active region. The relationship between dH/dt and microwave bursts is also discussed.

Authors: Yin Zhang, Baolin Tan, Yihua Yan
Projects: SoHO-MDI

Publication Status: accepted
Last Modified: 2009-09-08 07:34
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Yin Zhang   Submitted: 2008-06-24 01:59

In this letter we report a close relationship between the variations of the transport rate of the magnetic helicity dH/dt and the microwave burst. The latter may be regarded as a prompt signal of non-thermal energetic particles originated from the magnetic reconnection during solar flaring events. We analyze the observations of magnetograms of MDI/SOHO and SOT/Hinode, and the high-cadence microwave observation at 2.84 GHz obtained in Chinese Solar Broadband Radiospectrometer (SRBS/Huairou) of a flare/CME event which occurred in Active Region NOAA 10930 on 2006 December 13. We find that there is a sharp jump of dH/dt around the onset and quench of the microwave burst at the frequency of 2.84 GHz: the rate of dH/dt changes from negative to positive around the start of the eruption and recovers to negative when the eruption stopped. Furthermore the temporal profile of dH/dt is consistent with that of the microwave burst. These results manifest that sharp variations of dH/dt are closely related to the solar eruption.

Authors: Y. Zhang., B. L. Tan, and Y. H. Yan
Projects: None

Publication Status: accepted
Last Modified: 2008-06-24 08:00
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Yin Zhang   Submitted: 2008-06-24 01:59

In this letter we report a close relationship between the variations of the transport rate of the magnetic helicity dH/dt and the microwave burst. The latter may be regarded as a prompt signal of non-thermal energetic particles originated from the magnetic reconnection during solar flaring events. We analyze the observations of magnetograms of MDI/SOHO and SOT/Hinode, and the high-cadence microwave observation at 2.84 GHz obtained in Chinese Solar Broadband Radiospectrometer (SRBS/Huairou) of a flare/CME event which occurred in Active Region NOAA 10930 on 2006 December 13. We find that there is a sharp jump of dH/dt around the onset and quench of the microwave burst at the frequency of 2.84 GHz: the rate of dH/dt changes from negative to positive around the start of the eruption and recovers to negative when the eruption stopped. Furthermore the temporal profile of dH/dt is consistent with that of the microwave burst. These results manifest that sharp variations of dH/dt are closely related to the solar eruption.

Authors: Y. Zhang., B. L. Tan, and Y. H. Yan
Projects: Hinode/SOT

Publication Status: accepted
Last Modified: 2008-07-09 17:34
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Subject will be restored when possible  

Yin Zhang   Submitted: 2008-06-24 01:59

In this letter we report a close relationship between the variations of the transport rate of the magnetic helicity dH/dt and the microwave burst. The latter may be regarded as a prompt signal of non-thermal energetic particles originated from the magnetic reconnection during solar flaring events. We analyze the observations of magnetograms of MDI/SOHO and SOT/Hinode, and the high-cadence microwave observation at 2.84 GHz obtained in Chinese Solar Broadband Radiospectrometer (SRBS/Huairou) of a flare/CME event which occurred in Active Region NOAA 10930 on 2006 December 13. We find that there is a sharp jump of dH/dt around the onset and quench of the microwave burst at the frequency of 2.84 GHz: the rate of dH/dt changes from negative to positive around the start of the eruption and recovers to negative when the eruption stopped. Furthermore the temporal profile of dH/dt is consistent with that of the microwave burst. These results manifest that sharp variations of dH/dt are closely related to the solar eruption.

Authors: Y. Zhang., B. L. Tan, and Y. H. Yan
Projects: Hinode/SOT,SoHO-MDI

Publication Status: accepted
Last Modified: 2008-09-23 20:59
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Subject will be restored when possible  

Yin Zhang   Submitted: 2008-06-24 01:59

In this letter we report a close relationship between the variations of the transport rate of the magnetic helicity dH/dt and the microwave burst. The latter may be regarded as a prompt signal of non-thermal energetic particles originated from the magnetic reconnection during solar flaring events. We analyze the observations of magnetograms of MDI/SOHO and SOT/Hinode, and the high-cadence microwave observation at 2.84 GHz obtained in Chinese Solar Broadband Radiospectrometer (SRBS/Huairou) of a flare/CME event which occurred in Active Region NOAA 10930 on 2006 December 13. We find that there is a sharp jump of dH/dt around the onset and quench of the microwave burst at the frequency of 2.84 GHz: the rate of dH/dt changes from negative to positive around the start of the eruption and recovers to negative when the eruption stopped. Furthermore the temporal profile of dH/dt is consistent with that of the microwave burst. These results manifest that sharp variations of dH/dt are closely related to the solar eruption.

Authors: Y. Zhang., B. L. Tan, and Y. H. Yan
Projects:

Publication Status: ApJL, in press
Last Modified: 2008-07-09 17:42
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Correlation Between Sharp Variation of the Transport Rate of Magnetic Helicity and Solar Eruptive Events  

Yin Zhang   Submitted: 2008-06-24 01:59

In this letter we report a close relationship between the variations of the transport rate of the magnetic helicity dH/dt and the microwave burst. The latter may be regarded as a prompt signal of non-thermal energetic particles originated from the magnetic reconnection during solar flaring events. We analyze the observations of magnetograms of MDI/SOHO and SOT/Hinode, and the high-cadence microwave observation at 2.84 GHz obtained in Chinese Solar Broadband Radiospectrometer (SRBS/Huairou) of a flare/CME event which occurred in Active Region NOAA 10930 on 2006 December 13. We find that there is a sharp jump of dH/dt around the onset and quench of the microwave burst at the frequency of 2.84 GHz: the rate of dH/dt changes from negative to positive around the start of the eruption and recovers to negative when the eruption stopped. Furthermore the temporal profile of dH/dt is consistent with that of the microwave burst. These results manifest that sharp variations of dH/dt are closely related to the solar eruption.

Authors: Y. Zhang., B. L. Tan, and Y. H. Yan
Projects: Hinode/SOT,SoHO-MDI

Publication Status: ApJL, in press
Last Modified: 2008-09-23 20:59
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A Statistical Study on the Relationship between the Transport Rate of Magnetic Helicity and Solar Flares
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Correlation Between Sharp Variation of the Transport Rate of Magnetic Helicity and Solar Eruptive Events

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