ИЗМЕНЕНИЯ МАГНИТНОЙ СПИРАЛЬНОСТИ В

СОЛНЕЧНОМ ЦИКЛЕ

Kirill Kuzanyan

ИЗМИРАН, Россия

Zhang H., Gao Yu

Национальные Астрономические Обсерватории АН КНР

Question:

Can we learn more

of solar activity looking at

magnetic helicity?

Dynamo model with evolution of HelicityMagnetic field

generation (Parker Dynamo)

Parameterized equation

Generation of Helicity

20 years systematic monitoring of the solar vector magnetic fields in

active regions taken at Huairou Solar observing station, China

(1987-2006)More observations from Mitaka (Japan) and also Mees, MSFC (USA) etc., but only Huairou data systematically cover 20 years period.

So, theory requires the mirror asymmetry to be the same from

cycle to cycle!

How to measure it ?

observations

Observable !

Photospheric vector magnetogram of AR 10930 (SOT at Hinode); 2006 Dec 11-12 at 23:10:06-00:13:17UT.

AR 10930: HC over the filtergram; positive/negative: a typical AR.

The filtergram of AR 10930; contours of current helicity HC for positive (negative) values shown in red (green), corresponding to absolute values of 0.2, 0.5, 1.0, 4.0 G2/m, respectively. The field of view is 104''80''.

Observations and Data Reduction

• 983 active regions; 6630 vector magnetograms observed at Huairou Solar Observing Station;

• Time ranges from 1988 to 2005;

• Time average: 2 year data bins;

• Latitudinal: Northern hemisphere and Southern hemisphere (7 degree bins);

Helicity overlaid with butterfly diagram

Force free factor overlaid with butterfly diagram

Compare: Qualitatively, the both quantities are distributed in a similar manner. So, despite the noisy nature of the data, accuracy of measurements is reliable.

THE MAIN RESULT

• Current helicity and twist follow the propagation of the magnetic activity dynamo waves recorded by sunspots. The mirror asymmetry plays an important role in the solar dynamo mechanism.

Observable properties of helicity

• Anti-symmetric over the solar equator

• Cyclic variation 11 years (not 22 years!)

• Time lag with respect to sunspots is about 2

years ahead , not behind! (confront with

dynamo theory)

• Systematic sign inversion of helicity

(a) at the beginning of the cycle

(b) at the end of the cycle

Simple self-consistent dynamo model with evolution

of helicity (dynamical nonlinear dynamo)

Kleeorin, Kuzanyan, Moss, Sokoloff, Rogazhevsky, Zhang, A&A, 2003;and a series of publications of the authors thereafter in 2005-2009

Choice of Parameter Range (Example)

LATITUDE

HELICITY

C=0.01- ok!

C=0.1

too high value

FURTHER PLAN

• Include meridional circulation in order to see its effect on

(a) latitudinal extent of helicity versus sunspots and

(b) the time lag between helicity and sunspots

Kleeorin et al. 2003

EVOLUTION OF HELICITY WITH

TIME(Northern Hemisphere N)

Diffusion Time Units

S

N

Sunspot Group Number

Magnetic Energy

HELICITY

~1988 ~1997

Summary

• Helicity helps in

development of self-

consistent dynamo

models!

Thank you!