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, NAOJ2: Kyoto University

3: NASA/GSFC4: STE-Lab., Nagoya University

CSWM Workshop @Yokohama2006 November 13 - 17

2005-August-24 Storm2 M-class flares

strong geo-magnetic stormDst ~ -216 nT

Flares CMEs

Focusing on the features of the sun (photosphere and corona)

movie of SOHO/MDI magnetogram

Birth & Evolution of NOAA 10798

emergence!

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

NSNS

N S

NS

Soft X-Ray Lightcurve (GOES)

3 M-class flare occurred We focus on the first 2 flares on 2005-Aug-22

emergence

22-Aug

Filament Formation

From H images, we can identify a filament whose axial field directs south

southward magnetic field

Anemone of NOAA 10798

NOAA 10798 is a large and complex AR

3 M-class flares, CMEs occurred

SOHO/EIT 195A image

anemone structure

CH

Anemone Structure

anemone is mainly an active region that appears inside a coronal hole

nest of (gigantic) jets (not so active)

Shibata et al. (1994)

sea anemone

2 M-Class Flares

Near southwest limb flare1: (S11 W54) flare2: (S12 W60)

Both are long duration events (LDEs)

Clear arcade structure can be seenMovie of SOHO/EIT (195A)

flare1M2.6

flare2M5.6

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

CME 1

CME 2

LASCO/C2 – EIT LASCO/C3 diff

Interplanetary Disturbances

ACE data shock: 8/24 05:30UT

very complex structure

strong southward magnetic field: –50 nT

merging of 2 CMEs

n [cm-3]

V [km/s]

|B| [nT]

50

700

50

Bx [nT]

By [nT]

Bz [nT]

–50

Dst

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 position1st CME : 1200 km/s, 2nd CME : 2400 km/s

CME speeds were extremely fastStrong southward magnetic field region

H filament whose axial field directs southward was formed

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 expandHalo CMEsHigh speed CMEsGeo-effective CMEs

AR: active regionCH: coronal hole

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)