- Title
- Evolution of the magnetic field and flows of solar active regions with persistent magnetic bipoles before emergence
- Creator
- Alley, C.S.; Schunker, H.
- Relation
- ARC.FT220100330
- Relation
- Publications of the Astronomical Society of Australia Vol. 40, no. e059
- Publisher Link
- http://dx.doi.org/10.1017/pasa.2023.52
- Publisher
- Cambridge University Press
- Resource Type
- journal article
- Date
- 2023
- Description
- Magnetic active regions on the Sun are harbingers of space weather. Understanding the physics of how they form and evolve will improve space weather forecasting. Our aim is to characterise the surface magnetic field and flows for a sample of active regions with persistent magnetic bipoles prior to emergence. We identified 42 emerging active regions (EARs), in the Solar Dynamics Observatory Helioseismic Emerging Active Region survey (Schunker et al. 2016, A&A. 595, A107), associated with small magnetic bipoles at least one day before the time of emergence. We then identified a contrasting sample of 42 EARs that emerge more abruptly without bipoles before emergence. We computed the supergranulation-scale surface flows using helioseismic holography. We averaged the flow maps and magnetic field maps over all active regions in each sample at each time interval from 2 d before emergence to 1 d after. We found that EARs associated with a persistent pre-emergence bipole evolve to be, on average, lower flux active regions than EARs that emerge more abruptly. Further, we found that the EARs that emerge more abruptly do so with a diverging flow of (3±0.6)×10−6 s−1 on the order of 50–100 ms−1. Our results show that there is a statistical dependence of the surface flow signature throughout the emergence process on the maximum magnetic flux of the active region.
- Subject
- sun; magnetic fields; helioseismology; activity; sunspots
- Identifier
- http://hdl.handle.net/1959.13/1506410
- Identifier
- uon:55862
- Identifier
- ISSN:1448-6083
- Rights
- © The Author(s), 2023. Published by Cambridge University Press on behalf of the Astronomical Society of Australia. 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.
- Language
- eng
- Full Text
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