GLOBAL ASYMMETRY GLOBAL ASYMMETRY OF THE SUN OF THE SUN

OBSERVED IN THE EXTREME OBSERVED IN THE EXTREME ULTRAVIOLET RADIATIONULTRAVIOLET RADIATION

A. N. Zhukov¹’², I. S. Veselovsky², J.-F. Hochedez¹, F. Clette¹,

O. A. Panasenco², P. Cugnon¹

¹Royal Observatory of Belgium Avenue Circulaire 3, B–1180 Brussels, Belgium

²Institute of Nuclear Physics, Moscow State University Moscow 119899, Russia

Variations of integral intensity of full resolution SOHO/EIT images (1024×1024 pixels); January 1996 – February 2001, one image per day.

18–Nov–1996 07–Dec–1996coronal holes: –8%; “quiet Sun”: +60%; active regions and bright points: +48%

171 ÅFe IX/X18–Nov–1996

304 ÅHe II20–May–2000

195 ÅFe XII22–Sep–1996

284 ÅFe XV12–Apr–1999

MIN MAX

I I I

I I I

N I N I N I

N I N I N I

MIN MAX

I I I

I I I

N I N I N I

N I N I N I

Rotation QS AR CH

Nov – Dec ’96 60 % 48 % –8 %

Apr ’99 8 % 97 % –5 %

Jan 2000 12 % 96 % –8 %

May 2000 –1 % 105 % –4 %

Rotation QS AR CH

Nov – Dec ’96 28 % 78 % –6 %

Apr ’99 6 % 97 % –3 %

Jan 2000 10 % 101 % –11 %

May 2000 3 % 103 % –6 %

Rotation QS AR CH

Nov – Dec ’96 69 % 63 % –32 %

Apr ’99 15 % 102 % –17 %

Jan 2000 7 % 102 % –9 %

May 2000 –3 % 113 % –10 %

Rotation QS AR CH

Nov – Dec ’96 62 % 69 % –31 %

Apr ’99 4 % 110 % –14 %

Jan 2000 0 % 111 % –11 %

May 2000 –1 % 112 % –11 %

195 Å 171 Å

284 Å 304 Å

Contributions of different solar structures to the variations of the solar disc integral intensity in the Fe XII line (195 Å).

Contributions of different solar structures to the variations of the solar disc integral intensity in the Fe IX/X line (171 Å).

Contributions of different solar structures to the variations of the solar disc integral intensity in the Fe XV line (284 Å).

Contributions of different solar structures to the variations of the solar disc integral intensity in the He II line (304 Å).

Variations of the average intensity of different solar structures in the Fe XII line (195 Å).

Variations of the average intensity of different solar structures in the Fe IX/X line (171 Å).

Variations of the average intensity of different solar structures in the Fe XV line (284 Å).

Variations of the average intensity of different solar structures in the He II line (304 Å).

CONCLUSIONS

• Variations of the integral intensity of the EUV “quiet Sun” exhibit rotational modulation, i. e. global

longitudinal asymmetry.

• During the epoch of low solar activity the contribution of the “quiet Sun” to the rotational modulation of the integral solar disc

intensity is comparable to the contribution of active regions and bright points.

• The average intensity of the “quiet Sun” exhibits the rotational modulation at least throughout half of the solar cycle observed by SOHO.