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Collection of Emerging Active Regions That Produce Flares/CMEs

I. Events

1. X2.2 flare in AR 11158 on 2011-02-15

Fig. 1a: GOES X-rays Fig. 1b: A halo CME

This X2.2 flare (see Fig. 1a)started at 01:44:00, peaked at 01:56:00, and ended at 02:06:00, 2011 Feburary 15. A halo CME (v = 834 km/s) was associated with this flare (Fig. 1b. This running difference is from Space Weather Lab at GMU. A magnetic cloud (MC) and corotating interaction regions (CIR) are detected at 1 AU at 03:00 19 Feburary 2011 (see GMU CME/ICME List). No significant negative DST was measured.

Fig. 2: Full-disk magnetogram on 02/14/2011.

No big active regions were on the solar disk most of time during disk passage of AR 11158 ( see Fig. 2). A full-disk magnetogram movie can be viewed by Full-disk movie, along with a movie of Br in AR 11158 AR 11158 Br movie.

2. C3.7 flare in AR 11577 on 2012-09-27

Fig. 3a: GOES X-rays Fig. 3b: A halo CME

The C3.7 flare ( Fig. 3a) started at 23:36, peaked at 23:57 2012-09-27, and ended at 00:34 2012-09-28. A halo CME (v = 343 km/s; Fig. 3b) was associated with it. Shock front (SH) and CME ejecta front (EJ) were detected at 12:00 UT 2012-10-01 at 1 AU that was suggested to be associated with this solar event (see GMU CME/ICME List at GMU).

Fig. 4a: Full-disk magnetogram Fig. 4b: Harp image

AR 11577 is a small emerging active region ( Fig. 4a). It began to emerge on 2012-09-22, and decayed quickly in the following days. It became plage-like features at the beginning of 2012-09-27, and began the second emerging thereafter. This flare was occurred as the second emergence started (see the movie Full-disk movie). A Br movie of AR 11577 is here. There was another mature active region (AR 11575) close to AR 11577 ( Fig. 4b). Model of this event might be of difficulty.

3. X1.3 flare in AR 11429 on 2012-03-07

AR 11429 is not an emerging active region during its disk passage. An emerging active region AR 11430 was near AR 11429. Studying magnetic connectivity between them, and further exploring underlying effect of emergence of AR 11430 that may apply to triggering the flare might be of interest.

Fig. 5a: GOES X-rays Fig. 5b: A halo CME

The X1.3 flare occurred at 01:05, peaked at 01:14, and ended at 01:23 2012-03-07. A halo CME (v = 854 km/s) was associated with this flare. SH and EJ were detected at 1 AU at 20 UT 2012-03-08 (see GMU CME/ICME List at GMU). DST was measured to be -133.

Fig. 6a: Full-disk magnetogram Fig. 6b: Harp

There are three active regions on the disk while the flare occurrred. Emergence and evolution of AR 11430 can be viewed from a full-disk magnetic field movie. A Br-movie of ARs 11429 and 11430 is here.

4. Emerging active region AR 11928 from 2013-12-16 to 2013-12-21

Fig. 7: GOES X-rays.

The emerging active region emerged on 2013-12-16, and underwent dramatic evolution since then It produced six M-class and many C-class flares ( see Fig. 7). Two flares, one is a M1.3 flare occurred at 23:44 UT 2013-12-22T and the other C7.9 flare at 07:53 UT 2013-12-23, may be associated with partial halo CMEs. While the active region was near the south-western limb ( Fig. 8a), one of the said CME propogated toward the east ( Fig. 8b), and the other toward north-western ( Fig. 8c). Association of the flares and CMEs are to be examined.

Fig. 8a: Full-disk magnetogram Fig. 8b: CME-1 Fig. 8c: CME-2

There was a small sheath region detected at 1 AU at 3:30 UT December 25, 2013. ``Starting around 5:00 UT and lasting until approximately 18:00 UT there is a region of strong total B, with a very steady negative Bz and clear rotations in Bx and By (see Fig. 9). The Velocity is only around 300 Km/s, so it isn't very fast at all (and is pretty similar to the ambient solar wind), but over the same time region there is a gradual decline in velocity from 330 to 270 km/s, consistent with ICME expansion. (Phil Hess at GMU)''

Fig. 9: Magnetic field at 1 AU

Full-disk magnetic field movie is here. Br movie of AR 11928 is here.

II. Conclusion

While other events contain uncertainties one way or the other, AR 11158 appears to provide a clean case with much less uncertainties. AR 11158 might be a good choice though it has been intensively analyzed.