Studies on Twisted Magnetic Flux Bundles by Solar Optical Telescope (SOT)

Takako T. ISHII

Kwasan Observatory, Kyoto-U.

Contents;

・ Our previous studies

・ Advantage of Solar-B

Our previous studies

We have studied what is the key process to trigger the major solar flares using observational data of the evolution of active regions.

Key question: What is the common magnetic field configuration among flare-productive active regions ?

We have constructed schematic models of emerging magnetic flux bundles based on sunspot proper motions.

Photosphere Chromosphere

Method Emerging magnetic flux tube

photosphere

photosphere

Bipolar pair of sunspots

proper motion

proper motion

(H-alpha center)

Data analysis

・ Domeless Solar Telescope (DST) 　 at Hida Observatory, Kyoto-U.　⇒ H-alpha images by Lyot filter ・ TRACE White light images ⇒ and EUV images・ SOHO / MDI 　⇒ Magnetograms and Intensitygrams

Evolution of active regions (pair identification, sunspot proper motion)Flare activity (energy storage, trigger)

Ishii et al. (2000) PASJ, 52, 337

・ NOAA 4201 (1983 June) Ishii et al. 2000 ・ NOAA 5395 (1989 Mar.) Ishii et al. 1998・ NOAA 9026 (2000 June) Kurokawa et al. 2002・ NOAA 9236 (2000 Nov.) Ishii et al. 2002

For several active regions, we found that the emergence of twisted magnetic flux bundles is the key to highproductivity of major flares.

NOAA 9236 (Face-on movie)

gray scale: intensitygramcontour: magnetogram

level: 500 Gaussred: positiveblue: negative

20 degrees in heliographic coordinate

SOHO / MDI Full disk(magnetogram, intensitygram)1 pixel = about 2 arcsec

TRACE white lightMDI high resolution 1 pixel = 0.5 arcsec

200,000 km

NOAA 9236 (Face-on movie)

gray scale: white lightcontour: magnetogram

level: 500 Gaussred: positiveblue: negative

100 arcsec (70,000 km)

TRACE white lightMDI high resolution(Longitudinal magnetogram)Resolution : 1.0 arcsec

Solar-B / SOTVector-magnetogramResolution: 0.2 arcsec

SOT Field of View

1 pixel = 0.08 arcsec

Field of View (FOV)⇒max: 　　 328’’×164’’

～ 4 K×2 K CCD

Full disk Sun

SOT FOVmax

NOAA 92362000-Nov-24

06:24 UT

Full disk Sun

Cadence

<Example>SOHO MDI full disk daily evolution

East-limb West-limb 11 daysE 45 deg. W 45 deg. 7 days

・ Magnetograms 15 images / day ( one image / 90 min.)

OK.・ Intensitygrams

4 images / day ( one image / 6 hours)a little bit poor.

AttentionTrigger of flares:

Magnetic fields・ Magnetic shear

development・ Helicity injection

Sunspots ・ Rotational motion of sunspots　 (vortex-like motions of satellite spots, 　 penetration into opposite polarity region, 　 rotation of magnetic neutral line)

NOAA 9026

200,000 km

Kurokawa et al. (2002)ApJ, 572, 598

SummarySubject:

Flare energy storage and triggering process.Twists of magnetic flux tubes.

Wavelength: White light & Vector magnetogram

Field of View: SOT Max (328’’×164’’)

Cadence:at least 15 images / day (1 image / 90min.)

Duration: at least One week ( E45° ～ W45°)