Issue |
Astron. Astrophys. Suppl. Ser.
Volume 131, Number 1, July 1998
|
|
---|---|---|
Page(s) | 99 - 104 | |
DOI | https://doi.org/10.1051/aas:1998254 | |
Published online | 15 July 1998 |
Statistical analysis of the X-ray flares (M ≥ 1) during the maximum period of solar cycle 22
1
CCAST (World Laboratory), P.O. Box 8730, Beijing, 100080, China
2
Yunnan Observatory, Kunming, China
3
Observatoire de Paris, Section de Meudon, URA 2080, 92195 Meudon Principal Cedex, France
4
University of Oslo, Blindern, P.O. Box 1029, Norway
Send offprint request to: B. Schmieder
Received:
19
March
1997
Accepted:
11
February
1998
The data of the X-ray flare events of class during the
interval of 1987 to 1992 corresponding to the maximum period of the 22nd
solar cycle have been investigated to study the North-South (N-S) and
West-East (W-E)
asymmetries. During that period it has been shown the existence of a real
N-S asymmetry.
That confirms recent studies done by using other indicators, such as
sunspot areas (Oliver & Ballester 1994). The E-W asymmetry during that period
is not significant but
a non uniform flare distribution in longitude
has been evidenced. That result is also in good agreement with the work
made by Joshi (1995) using Hα flares for the same time period.
We have shown that the behaviour of the reverse tendency of Solar Cycle 21 to
exhibit a predominance of the southern hemisphere in the N-S asymmetry compared
to the previous Solar Cycles (19 and 20)
is maintained for Solar Cycle 22. A long period cycle of the N-S asymmetry
could be suspected.
Key words: Sun: activity / Sun: flares / Sun: X-rays
© European Southern Observatory (ESO), 1998