preprints.org > physical sciences > astronomy and astrophysics > doi: 10.20944/preprints202306.0783.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 10 June 2023 / Approved: 12 June 2023 / Online: 12 June 2023 (07:20:58 CEST)

The details of the solar flare production mechanisms are not yet completely understood. One of the standing questions is the anisotropy of the X-ray flux, especially in strong flares. It can be studied indirectly by analysing the characteristics of flares at different positions on the visible disc. In this paper, the durations, peak and integral fluxes of strong (X-class) solar flares from cycles 22--25 are considered with respect to their apparent position on the Sun. It is found that there exists a significant north--south asymmetry in all three parameters, which also varies depending on the phase of the solar cycle (with general predominance of the south). This confirms the results of previous studies. A weaker and less significant east--west asymmetry is found as well, partly supported by literature. A previously undetected centre-to-limb asymmetry is reported (in favour of the limb) in all three parameters. All three asymmetries are enhanced during the solar minimum, which could hint at their connection to the large scale magnetic structuring of the Sun. The prevalence of strong solar flares near the limb at the solar minimum has clear space weather warning implications.

Sun: activity; Sun: flares; Sun: X-rays; gamma-rays

Physical Sciences, Astronomy and Astrophysics

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