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Complexity of emerging magnetic flux during lifetime of solar ephemeral regions

Published online by Cambridge University Press:  23 December 2024

Hanlin Yang Open the ORCID record for Hanlin Yang [Opens in a new window]
Hanlin Yang*
Affiliation:
Key Laboratory of Solar Activity and Space Weather, National Astronomical Observatories, Chinese Academy of Science, Beijing 100101, People’s Republic of China University of Chinese Academy of Sciences, 100049, Beijing, People’s Republic of China
*
email: [email protected]
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Abstract

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As a relatively active region, ephemeral region (ER) exhibits highly complex pattern of magnetic flux emergence. We aim to study detailed secondary flux emergences (SFEs) which we define as bipoles that their locations close to ERs and finally coalesce with ERs after a period. We study the SFEs during the whole process from emergence to decay of 5 ERs observed by the Helioseismic and Magnetic Imager (HMI) aboard Solar Dynamics Observatory (SDO). We find that the maximum unsigned magnetic flux for each of the ERs is around 1020 Mx. All ERs have tens of SFEs with an average emerging magnetic flux of approximately 5×1018 Mx. The frequency of normalized magnetic flux for all the SFEs follows a power law distribution with an index of -2.08. The majority of SFEs occur between the positive and negative polarities of ER, and their growth time is concentrated within one hour. The magnetic axis of SFEs also exhibits a random characteristic. We suggest that the relationship between SFEs and ERs can be understood by regarding the photospheric magnetic field observations as cross-sections of an emerging magnetic structure. Tracking the ERs’ evolution, we propose that the flux emergences are partially emerged Ω-loops, and that the SFEs in ERs may be sequent emergences from the bundle of flux tube of ERs.

Keywords

Sun: Solar Magnetic FieldSun: Magnetic BipolaritySun: Magnetic FluxSun: Solar Activity EffectsSun: Atmospheric heatingSun: Magnetic SignaturesSun: Network Analysis
Type
Contributed Paper
Information
Proceedings of the International Astronomical Union , Volume 19 , Symposium S365: Dynamics of Solar and Stellar Convection Zones and Atmospheres , December 2023 , pp. 303 - 310
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Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of International Astronomical Union

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