Searching for Evidence of Subchromospheric Magnetic Reconnection on the Sun
- Author(s)
- D. Baker, L. van Driel-Gesztelyi, A. W. James, P. Demoulin, A. S.H. To, M. Murabito, D. M. Long, D. H. Brooks, J. McKevitt, J. M. Laming, L. M. Green, S. L. Yardley, G. Valori, T. Mihailescu, S. A. Matthews, H. Kuniyoshi
- Abstract
Within the coronae of stars, abundances of those elements with low first ionization potential (FIP) often differ from their photospheric values. The coronae of the Sun and solar-type stars mostly show enhancements of low-FIP elements (the FIP effect) while more active stars such as M dwarfs have coronae generally characterized by the inverse-FIP (I-FIP) effect. Highly localized regions of I-FIP effect solar plasma have been observed by Hinode's EUV Imaging Spectrometer in a number of highly complex active regions (ARs), usually around strong light bridges of the umbrae of coalescing/merging sunspots. These observations can be interpreted in the context of the ponderomotive force fractionation model, which predicts that plasma with I-FIP effect composition is created by the refraction of waves coming from below the plasma fractionation region in the chromosphere. A plausible source of these waves is thought to be reconnection in the (high-plasma-β) subchromospheric magnetic field. In this study, we use the 3D visualization technique of Chintzoglou & Zhang combined with observations of localized I-FIP effect in the corona of AR 11504 to identify potential sites of such reconnection and its possible consequences in the solar atmosphere. We found subtle signatures of episodic heating and reconnection outflows in the expected places, in between magnetic flux tubes forming a light bridge, within the photosphere of the AR. Furthermore, on either side of the light bridge, we observed small antiparallel horizontal magnetic field components, supporting the possibility of reconnection occurring where we observe I-FIP plasma. When taken together with the I-FIP effect observations, these subtle signatures provide a compelling case for indirect observational evidence of reconnection below the fractionation layer of the chromosphere, however direct evidence remains elusive.
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- University College London, Université de recherche Paris Sciences et Lettres, Eötvös Loránd Research Network, Laboratoire Cogitamus, Science and Operations Department - Science Division (SCI-SC), INAF - Osservatorio Astronomico di Roma, Space Science Data Center (SSDC) - Agenzia Spaziale Italiana (ASI), Dublin City University, George Mason University, U.S. Naval Research Laboratory, Northumbria University, University of Reading, Donostia International Physics Center, Max Planck Institute for Solar System Research, University of Tokyo
- Journal
- Astrophysical Journal
- Volume
- 970
- ISSN
- 0004-637X
- DOI
- https://doi.org/10.3847/1538-4357/ad4a6e
- Publication date
- 07-2024
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103003 Astronomy, 103004 Astrophysics
- ASJC Scopus subject areas
- Astronomy and Astrophysics, Space and Planetary Science
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/975a33f7-c783-42ef-9206-ffead9ab0c73