A Quantitative Study on A Quantitative Study on Evolution of Solar Active Evolution of Solar Active

RegionsRegions

Guo Juan & Zhang Hongqi

Huairou Solar Observing Station,National Astronomical Observatories, CAS

OutlineOutline

Quantitative study on evolution of magnetic field in solar active regions (ARs)

Relationship between magnetic structural parameter of some flare-associated (CME-associated) ARs and flares (CMEs)

Quantitative study on evolution Quantitative study on evolution of magnetic field of ARsof magnetic field of ARs

Three parameters are used:

(1) Total flux (Fa)

(2) Tilt angle (Tilt)

(3) Structural parameter (Hu)

(be measured from line-of-sight magnetograms)

(1) Total flux(1) Total flux

Fa = |Fn|+|Fs|

Fa ~ describes the total flux of an AR

(2) Tilt(2) Tilt

tilt = arctan (δy /δx )

tilt ~ one of the measurable characteristics of solar ARs that gives us information about subsurface physical processes

The definition of tilt in the 23The definition of tilt in the 23rdrd solar cyclesolar cycle

in the north hemisphere in the south hemisphere

s

s

s sn

n

n

n ns

90

－ 90

1800

－ 90

90

0 180

(3) Structural parameter(3) Structural parameter

Hu = (Rs+Rn)/Rsn

Hu ~ describes the degree of isolation or mutual penetration of two polarities of an AR

Hu = (Rn+Rs)/Rns

= 0.6585

(Xs,Ys)

(Xn,Yn)Rs

Rn

Rns

well separated bipolar:

(Xs,Ys)

(Xn,Yn)

Rs

Rn

Rns

Hu = (Rn+Rs)/Rns

= 2.0969

highly packed bipolar:

Structural Parameter Structural Parameter (continued)(continued)

Hu < 1: well seperated bipolar Hu > 1: highly packed bipolar The higher the value of Hu is, the higher the

degree of the two polarities packed together. The good correlation between Hu and the

configuration of magnetic field suggests that we can describe the magnetic configuration of an AR quantitatively by Hu.

A summary of three ARsA summary of three ARsArea(10-6 hemi)

10488 27-Oct-03 N09E09 β Dko 270 3C 1M(N08 L291) 28-Oct-03 N08W04 βγδ Dkc 800 2C

29-Oct-03 N07W17 βγδ Fkc 1460 1C30-Oct-03 N08W28 βγδ Fkc 1750 3C 1M31-Oct-03 N08W42 βγδ Fkc 1570 4C 1M

10484 20-Oct-03 N05E40 βγδ Ekc 1420 7C 1M(N04 L355) 21-Oct-03 N04E26 βγδ Dkc 1720 3C 1M

22-Oct-03 N04E13 βγδ Ekc 1750 2M23-Oct-03 N04W00 βγδ Ekc 1750 3M24-Oct-03 N05W15 βγδ Ekc 1460 2C 1M25-Oct-03 N04W28 βγδ Dkc 1700 2C 2M26-Oct-03 N03W41 βγδ Ekc 1350 2M 1X

9026 4-Jun-00 N21E36 βγδ Fki 870 7C 1M(N21 L074) 5-Jun-00 N21E23 βγδ Ekc 820 1C

6-Jun-00 N20E10 βγδ Fki 800 5C 2M 2X7-Jun-00 N20E03 βγδ Fkc 630 3C 1X8-Jun-00 N22W17 βγδ Fai 470 5C9-Jun-00 N22W29 βγ Esi 400 1C10-Jun-00 N22W40 β Eao 200 1M

Spot class SXR flaresNOAA ARNo.

Data range Location Mag. class

AR10488AR10488

NOAA 10488

0. 5

1

1. 5

2

- 60 - 50 - 40 - 30 - 20 - 10 0 10

Ti l t

Hu

AR10484AR10484

NOAA 10484

1. 5

2

2. 5

3

- 20 - 10 0 10 20 30 40 50

Ti l t

Hu

AR 9026 AR 9026

NOAA 9026

1

1. 5

2

2. 5

- 30 - 20 - 10 0 10 20 30

Ti l t

Hu

Comparison of three ARsComparison of three ARs

0

0. 5

1

1. 5

2

2. 5

3

-60 -40 -20 0 20 40 60

Ti l t

Hu

10488104849026

SummarySummary Quantitative analysis shows characteristics of the

magnetic configurations and their evolutions of ARs. Three selected ARs show distinguished properties.

When ARs are of the same type with Mount Wilson Magnetic Classification, Hu gives different values:

NOAA 10488 mHu=1.23

NOAA 10484 mHu=2.18

NOAA 9026 mHu=1.40

Structural parameter and Structural parameter and solar major activitiessolar major activities

Magnetic gradient could be a viable proxy to predict where a major activity might occur (Falconer et al., 2003, JGR; Wang, H. M. et al., 2005, ApJ, submitted).

Structural parameter (Hu) is of the similar meaning with the magnetic gradient in some sense: the nearer the two polarities the higher the Hu, the near the two polarities the higher the magnetic gradient.

We believe that there must be close relationship between Hu and the occurrence of solar major activities.

Relationship between magnetic Relationship between magnetic structural parameter and flare indexstructural parameter and flare index

y = 0. 0011x + 0. 8472R2 = 0. 7287

0

1

2

3

4

5

0 500 1000 1500 2000 2500 3000 3500X- ray i ndex

mHu

Relationship between magnetic Relationship between magnetic structural parameter and CMEsstructural parameter and CMEs

54 CMEs originated from 26 ARs:

Hu<1: 21 CMEs 38.9%

Hu>1: 33 CMEs 61.1%

24 fastest CMEs ( >1000 m/s)： Hu<1: 4 CMEs 16.7%

Hu>1: 20 CMEs 83.3%

SummarySummary

There is close relationship between structural parameter and the occurrence of major activities.

Structural parameter may be a good proxy to predict whether an AR is likely to be major activities productive.

Thanks a lot!