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Anemone Structure of AR NOAA 10798 and Related Geo-Effective Flares and CMEs

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

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Anemone Structure of AR NOAA 10798 and Related Geo-Effective Flares and CMEs

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  1. Anemone Structure of AR NOAA 10798 and Related Geo-Effective Flares and CMEs A. Asai1(浅井 歩), T.T. Ishii2, K. Shibata2, N. Gopalswamy3 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 Flare • 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) CME Dst Index magnetic storm nT Dst ~ 216 nT 8/23 24 25 26 27

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

  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 S N S N highly twisted magnetic structure lies beneath the photosphere!? generate X17 flare in the next rotation NOAA 10798 N S S N

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

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

  8. 50 n [cm-3] Interplanetary Disturbance 700 V [km/s] • ACE data • shock: 8/24 05:30UT • very complex structure • strong southward magnetic field: –50 nT • merging of 2 CMEs? • CIR + shock? 50 |B| [nT] 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 2nd 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? Ha image obtained with SMART of Kyoto Univ. • From Ha images, we can identify a filament whose axial field directs south on 2006 August 21 N S SOHO/MDI

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

  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 N 37/55 = 67% 18/55 = 33% 15W SEP E W S 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) ODst < - 200 nT O - 300nT < Dst < - 200 nT O Dst < - 300 nT

  16. SEPイベント

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

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