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

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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
Anemone Structure of AR NOAA 10798 and Related Geo-Effective Flares and CMEsA. Asai1(浅井 歩), T.T. Ishii2, K. Shibata2, N. Gopalswamy31: Nobeyama Solar Radio Observatory, NAOJ2: Kyoto University3: NASA/GSFCCOSPAR2006-A-02406; D2.1-0023-06COSPAR 2006, Beijing, China 2006-July-19Today’s TopicFlare
  • 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)
  • CMEDst Indexmagnetic stormnTDst ~ 216 nT8/23 24 25 26 27Birth & Evolution of NOAA 10798emergence!movie of SOHO/MDI magnetogramFeature of NOAA 10798Emerged 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 hemisphereSNSNhighly twisted magnetic structure lies beneath the photosphere!?generate X17 flare in the next rotationNOAA 10798NSSNSoft X-Ray Lightcurve (GOES)
  • 3 M-class flare occurred
  • We focus on the first 2 flares on 2005-Aug-22
  • emergence22-AugNear southwest limbflare1: (S11 W54)flare2: (S12 W60)Both are long duration events (LDEs)Clear arcade structure can be seen2 M-Class Flaresflare2M5.6flare1M2.6Movie of SOHO/EIT (195A)Associated with the flares, Halo-type CMEs occurred08/22 01h (flare1: M2.6)CME1: 1200 km/s08/22 17h (flare2: M5.6)CME2: 2400 km/svery fast CME!Time interval is ~16hours, but the 2nd CME may catch up the 1st one2 Halo-CMEsSOHO/LASCO C350n [cm-3]Interplanetary Disturbance700V [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]–50DstEvent 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 detailSouthward 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 21NSSOHO/MDIAnemone Structure
  • anemone structure: active region that appears inside a coronal hole
  • nest of (gigantic) jets (not so active)
  • anemone structuresea anemoneCHSOHO/EIT 195A imageAnemone 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 CMEsAR: active regionCH: coronal holeSummary
  • 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)Thank you!Longitudes of Storm-related CMEsN37/55 = 67%18/55 = 33%15WSEPEWSEast-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 nTO - 300nT < Dst < - 200 nTO Dst < - 300 nTSEPイベントCoronal Features of NOAA 10798
  • SOHO/EIT (195A)
  • NOAA 1079810797CHNew AR appears in a small coronal hole
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