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Anemone Structure and Geo-Effective Flares/CMEs

Anemone Structure and Geo-Effective Flares/CMEs. A. Asai 1 , T.T. Ishii 2 , K. Shibata 2 , N. Gopalswamy 3 , R. Kataoka 4 , M. Oka 2 1: Nobeyama Solar Radio Observatory, NAOJ 2: Kyoto University 3: NASA/GSFC 4: STE-Lab., Nagoya University. CSWM Workshop @Yokohama 2006 November 13 - 17.

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Anemone Structure and Geo-Effective Flares/CMEs

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  1. Anemone Structure and Geo-Effective Flares/CMEs A. Asai1, T.T. Ishii2, K. Shibata2, N. Gopalswamy3, R. Kataoka4, M. Oka2 1: Nobeyama Solar Radio Observatory, NAOJ 2: Kyoto University 3: NASA/GSFC 4: STE-Lab., Nagoya University CSWM Workshop @Yokohama 2006 November 13 - 17

  2. 2005-August-24 Storm 2 M-class flares • Focusing on the features of the sun (photosphere and corona) Flares CMEs strong geo-magnetic storm Dst ~ -216 nT

  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. Filament Formation • From Ha images, we can identify a filament whose axial field directs south southward magnetic field

  7. Anemone of NOAA 10798 anemone structure • NOAA 10798 is a large and complex AR • 3 M-class flares, CMEs occurred CH SOHO/EIT 195A image

  8. Anemone Structure sea anemone • anemone is mainly an active region that appears inside a coronal hole • nest of (gigantic) jets (not so active) Shibata et al. (1994)

  9. 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 flare2 M5.6 flare1 M2.6 Movie of SOHO/EIT (195A)

  10. 2 Halo-CMEs 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 SOHO/LASCO C3

  11. LASCO/C2 – EIT LASCO/C3 diff CME 1 CME 2

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

  13. Event Summary • 2 LDE flares occurred on 2005 August 22 • NOAA 10798 was close to the west limb (~W60) • Halo-type CMEs occur regardless of the near-limb position • 1st CME : 1200 km/s, 2nd CME : 2400 km/s • CME speeds were extremely fast • Strong southward magnetic field region • Ha filament whose axial field directs southward was formed

  14. 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 density above the AR + Guided by open field line • Easy for ejections to expand Halo CMEs High speed CMEs Geo-effective CMEs AR: active region CH: coronal hole

  15. 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) big magnetic storm (2005 August 24)

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