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Magnetic Structures of Active Regions and their Link to Coronal Mass Ejections Vasyl Yurchyshyn, Big Bear Solar Observatory, Big Bear City, CA 92314, www.bbso.njit.edu/~vayur.

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Presentation on theme: "Magnetic Structures of Active Regions and their Link to Coronal Mass Ejections Vasyl Yurchyshyn, Big Bear Solar Observatory, Big Bear City, CA 92314, www.bbso.njit.edu/~vayur."— Presentation transcript:

1 Magnetic Structures of Active Regions and their Link to Coronal Mass Ejections Vasyl Yurchyshyn, Big Bear Solar Observatory, Big Bear City, CA 92314, www.bbso.njit.edu/~vayur Bz 55 deg (MFI) MC axis The active region’s magnetic field was mainly NS orientated and the left handed twist caused its axial field to be directed eastwardly. Because the ejecta had southwardly directed azimuthal component, this eruption was associated with a very strong geomagnetic storm. CME on July 14, 2000 – Bastille Day Flare CME on February 17, 2000 Bz 85 deg (MFI) MC axis The erupted filament D had the SN orientation, i.e. its axial field was directed northward. This AR was positively twisted and the azimuthal field was directed westward. This eruption did not cause any geomagnetic activity because no strong southwardly directed magnetic component was present in the erupted field. October 28 2003 X17 Event November 18, 2003 M5.7 Flare and CME Solar coronal mass ejections (CMEs) are a principal link that connect the chain of events in the solar atmosphere, interplanetary space and the earth's magnetosphere. When CMEs reach the earth, they may cause a significant magnetic perturbations, provided that their magnetic environment contains intensive southward magnetic fields. Earlier studies unanimously suggest that there is a correspondence between the erupted filaments and magnetic clouds (MC) at 1AU. Our study shows that in the case of active regions there also is the correspondence between the solar and interplanetary magnetic fields. Another conclusion is that the origin of the studied MCs is probably related to the local magnetic fields of the active region and the reconnection of the AR’s fields with the global large –scale field probably plays a minor role. The study further supports the idea that it is possible to predict the presence of the southward magnetic field in interplanetary ejecta. CME) result from global changes in solar magnetic fields, which are often accompanied by powerful energy release. Besides the strong emission from the flare core, remote emission (RB) is often observed in H alpha, EUV and X ray spectral lines and it is thought to be related to the large scale structure of the flare (Wang 2005). LaBonte (1976) and Tang & Moore (1982) showed that RBs, coincide with type III reverse slope (RS) radio bursts that are the descending part of U bursts and are generated by fast electrons channeled within large-scale, closed magnetic loops. It is suggested that interaction between the erupted core field and the surrounding fields of an active region is the reason for RBs to occur (Manoharan et al., 1996; Wang et al.. 2002; Yurchyshyn et al., 2004). Friday, May 13, 2005 M8.0 flare and CME The April 9 2001 M7.9 flare occurred in a delta-configuration at 1522UT as a two bright patches in Areas 2 and 3 located within the delta-sunspot. At 1524UT, when the two first Halpha patches have almost reached their maximum intensity, several additional Halpha RBs appeared (Areas 4, 5 and 1 at1528UT). BBSO magnetogram and linear force free lines (LFFF, alpha=0.01 arcsec -1 ) show that Area 1 was magnetically connected with the site of the flare (Area 2) as well as Area 4 was connected to Areas 3 and 5, where foot point of the post flare loop systems were located. The pre-flare Yohkoh and TRACE images provide observational evidence for these magnetic connections (indicated by the arrows). Thus, data suggest that the delta-sunspot was associated with two topologically independent magnetic fluxes that were not connected at the flare onset and direct magnetic connections (short and dark loops in the after-flare (TRACE image) within the delta-sunspot occurred only after the flare. The interplanetary shock, associated with the April 9 CME, is seen in ACE data at 1300-2230UT on April 11, while the structures, between 2230UT (April 11) and 0530UT (April 12), could be related to the April 9 eruption. It is interesting to note that a strong westward By component (green line) is present in the disturbance, which is expected from the quadruple reconnection model. Please, note that a flux rope model would predict a strong rotating By component and strong negative Bz. In the radio range, 4 strong quasi-periodic bursts were detected at 3GHz (peaks at 1526UT, 1530UT, 1537UT and 1545UT). Type II burst at 40-300 MHz were seen at 1525-1550UT, while type III bursts were detected at 1527-1540UT. Many fast type III RS bursts that looked as a descending part of the type U burst were observed during the flare, which indicates the motion of electrons along closed large-scale magnetic loops that passed through the reconnection site. Data suggests that this flare was a result of reconnection in the quadruple configuration that was realized in a delta-type magnetic topology. This suggestion differs from the current view that delta-sunspots are rising highly twisted kink-unstable magnetic flux tubes (Linton et al., 1998; Fan et al., 1999). In those models, the two opposite polarity sunpots that comprise the delta sunspot are connected and the eruption is thought to proceed according to the flux rope model (bipolar configuration) (Forbes & Isenberg 1991; Amari et al.,2000). April 9, 2001 M7.9 flare and CME BBSO H  1624UT BBSO H  1654UT BBSO H  +0.9 1711UT BBSO H  1738UT EIT 195A 1637UT EIT 195A 1657UT Post flare loop system CME old reconnecting loops Estimated orientation and directions of the magnetic field in the associated left handed (alpha<0) magnetic cloud BBSO H  May 13, 2005 1616UT AR NOAA 0759 was located nearly at the disk center on May 13, 2005. It produced a moderate M8.0 flare and a very fast CME (v~1500km/s). The flare seems to be caused by reconnection between to large magnetic fluxes (indicated by the green lines), which produced post flare loops system (pink) and large-scale loop system that most probably has erupted and gave rise to a the CME. The linear force free modeling (LFFF) showed that the predominant twist in this AR was negative (left handed) and we estimated that the CME should have its axial field pointed eastward, while the polarity of the magnetic field at its leading edge should be southward (see the green cylinder in the figure above). If so, ACE measurements should then detect Bz component rotating from being negative (S) to positive to (N), while the By component should be predominantly positive (eastward). Observed magnetic cloud (plots to the left, shaded area) fully supports this prediction. ACE data show that Bz component indeed rotated (yellow), while the By was positive (eastward). Thus, this observed SEN magnetic cloud very well agrees with the orientation and field directions in the active region. These data also suggest that, at least, some CMEs and the associated MCs are formed via reconnection between active region’s magnetic fields and the surrounding coronal fields play a minor role in determining their spatial parameters. flare ribbons The X17.2/4B flare on Oct 28 2003 was associated with the erupted field of negative helicity. The blue arrows indicate the direction of the axial and azimuthal fields in the post flare arcade. Thus, data suggest that the associated interplanetary ejecta may have a southward Bz component. The observed magnetic cloud (green cylinder) at 1AU was southwardly oriented, as expected, and it had negative helicity. filament, which suggests that the orientation of the ejecta may not coincide with the that inferred from the PFL. We were able to identify the foot points of the erupted filament. The comparison of the solar and MC data shows that the MC was co- aligned with the foot points of the filament (yellow dots), which indicates that the MC was associated with the local fields of the active region. The M3.9/2N flare and the CME on Nov 18 2003 caused one of the strongest geomagnetic storms of solar cycle 23. Although the axial field of the post-flare loops system (PFL) was east-west oriented (blue arrow) and the system had positive helicity, the flare emission stretched along the dark H 


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