1. Anemone Structure of AR NOAA 10798 and Related Geo-Effective Flares and CMEs A. Asai 1 ( 浅井 歩 ), T.T. Ishii 2, K. Shibata 2, N. Gopalswamy 3 1: Nobeyama Solar Radio Observatory, NAOJ 2: Kyoto University 3: NASA/GSFC COSPAR2006-A-02406; D2.1-0023-06 COSPAR 2006, Beijing, China 2006-July-19

2. Today’s Topic  A magnetic storm (2005 August 24) and the related events  Birth and evolution of AR NOAA 10798  Flares and CMEs (2005 August 22)  Magnetic storm (2005 August 24)  Focusing on the features of the sun (photosphere and corona) 8/23 24 25 26 27 Dst Index nT Dst ~ 216 nT Flare CME magnetic storm

3. movie of SOHO/MDI magnetogram Birth & Evolution of NOAA 10798 emergence!

4. Feature of NOAA 10798 Emerged pair violates the Hale’s polarity law! the order of N/S polarity regions with respect to the east-west direction is determined in a given hemisphere  highly twisted magnetic structure lies beneath the photosphere!?  generate X17 flare in the next rotation NOAA 10798 N S N S N S N S

5. Soft X-Ray Lightcurve (GOES)  3 M-class flare occurred  We focus on the first 2 flares on 2005-Aug-22 emergence 22-Aug

6. 2 M-Class Flares  Near southwest limb  flare1: (S11 W54)  flare2: (S12 W60)  Both are long duration events (LDEs)  Clear arcade structure can be seen Movie of SOHO/EIT (195A) flare1 M2.6 flare2 M5.6

7. 2 Halo-CMEs  Associated with the flares, Halo-type CMEs occurred  08/22 01 h (flare1: M2.6)  CME1: 1200 km/s  08/22 17 h (flare2: M5.6)  CME2: 2400 km/s  very fast CME!  Time interval is ~16hours, but the 2 nd CME may catch up the 1 st one SOHO/LASCO C3

8. Interplanetary Disturbance  ACE data  shock: 8/24 05:30UT  very complex structure  strong southward magnetic field: –50 nT  merging of 2 CMEs?  CIR + shock? n [cm -3 ] V [km/s] |B| [nT] 50 700 50 Bx [nT] By [nT] Bz [nT] –50 Dst

9. Event Summary  2 LDE flares occurred on 2005 August 22  NOAA 10798 was close to the west limb (W60)  Halo-type CMEs  The 2 nd CME is especially fast (2400 km/s)  Strong southward magnetic field region  What was the origin of the southward magnetic field?  Why did halo-type CMEs occur regardless of the near-limb position?  Why were so fast CMEs?  Examine the features of the active region in more detail

10. Southward Magnetic Field?  From H  images, we can identify a filament whose axial field directs south N S on 2006 August 21 H  image obtained with SMART of Kyoto Univ. SOHO/MDI

11. Anemone Structure  anemone structure: active region that appears inside a coronal hole  nest of (gigantic) jets (not so active) sea anemone SOHO/EIT 195A image anemone structure CH

12. Anemone Structure and Flares/CMEs  For a small AR, CH works to collimate the ejections  In the case of NOAA 10798, a small CH and quite a big AR…  Low magnetic pressure above the AR  Easy for ejections to expand  Halo CMEs  High speed CMEs AR: active region CH: coronal hole

13. Summary  NOAA 10798  has a potentially complex structure (violating the Hale’s polarity law)  emerged in a small coronal hole  anemone structure  formed filaments, whose the axial field is southward  generated 3 M-class flares (2005 August 22–23),  followed by Halo-type CMEs  CMEs are very fast, and are widely spread  strong southward magnetic field (2 CMEs / CIR + shock)  big magnetic storm (2005 August 24)

14. Thank you!

15. Longitudes of Storm-related CMEs 15W N S WE O Dst < - 200 nT O - 300nT < Dst < - 200 nT O Dst < - 300 nT East-West Asymmetry of solar sources is confirmed (Wang et al. 2002; Zhang et al. 2003) Larger storms (Dst < -200 nT) seem to occur Close to the disk center (±15 deg) 37/55 = 67% 18/55 = 33% SEP

16. SEP イベント

17. Coronal Features of NOAA 10798  SOHO/EIT (195A) NOAA 10798 CH 10797 New AR appears in a small coronal hole