Understanding the Magnetic Field and Plasma-β along Umbral Fan Loops Traced Using 3 Minute Slow Waves

Plasma- β is an important fundamental physical quantity in solar plasma physics, which determines the dominating process in the solar atmosphere, i.e., magnetic or thermodynamic processes. Here, for the first time, we provide variations of magnetic field and plasma- β along magnetically structured l...

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Main Authors: Ananya Rawat, Girjesh Gupta, Tom Van Doorsselaere, S. Krishna Prasad, Robertus Erdélyi
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal Letters
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Online Access:https://doi.org/10.3847/2041-8213/ade9be
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author Ananya Rawat
Girjesh Gupta
Tom Van Doorsselaere
S. Krishna Prasad
Robertus Erdélyi
author_facet Ananya Rawat
Girjesh Gupta
Tom Van Doorsselaere
S. Krishna Prasad
Robertus Erdélyi
author_sort Ananya Rawat
collection DOAJ
description Plasma- β is an important fundamental physical quantity in solar plasma physics, which determines the dominating process in the solar atmosphere, i.e., magnetic or thermodynamic processes. Here, for the first time, we provide variations of magnetic field and plasma- β along magnetically structured loops from the photosphere to the corona. We have selected several fan loops rooted in sunspot umbra observed simultaneously by the Interface Region Imaging Spectrograph and Solar Dynamics Observatory. The 3 minute slow waves enabled us to trace and analyze several fan loops with cross-sectional areas in the lower atmosphere and locate their footpoints at the photosphere. We find the rms magnetic field strengths in the range 1596–2269 G at the photospheric footpoints of the fan loops, which decrease rapidly to 158–236 G at the coronal footpoints. We estimated the plasma- β at the photospheric and coronal footpoints in the range 0.2–0.5 and 0.0001–0.001, respectively. We found plasma- β < 1 along the whole loop, whereas the plasma- β ≈ 1 layer is found to be at subphotospheric heights. We compared our findings for isolated individual fan loops with a previously established model for active regions and found an almost similar pattern in variations with height, but with different plasma- β values. Our results demonstrate the seismological potential of 3 minute slow waves omnipresent in the umbral sunspot atmosphere to probe and map isolated loops and determine magnetic field and plasma- β along these loops. The obtained parameters provide crucial ingredients for the theoretical modeling of the umbral atmosphere and wave dynamics along loops.
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spelling doaj-art-35db63f533cd497f90478dbc49a07b992025-08-20T03:51:08ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019881L2610.3847/2041-8213/ade9beUnderstanding the Magnetic Field and Plasma-β along Umbral Fan Loops Traced Using 3 Minute Slow WavesAnanya Rawat0https://orcid.org/0009-0005-9936-9928Girjesh Gupta1https://orcid.org/0000-0002-0437-6107Tom Van Doorsselaere2https://orcid.org/0000-0001-9628-4113S. Krishna Prasad3https://orcid.org/0000-0002-0735-4501Robertus Erdélyi4https://orcid.org/0000-0003-3439-4127Udaipur Solar Observatory, Physical Research Laboratory , Dewali, Badi Road, Udaipur 313001, India ; ananyarawat@prl.res.in; Department of Physics, Indian Institute of Technology Gandhinagar , Palaj, Gandhinagar 382355, IndiaUdaipur Solar Observatory, Physical Research Laboratory , Dewali, Badi Road, Udaipur 313001, India ; ananyarawat@prl.res.inCentre for mathematical Plasma Astrophysics , Department of Mathematics, KU Leuven, 3001 Leuven, BelgiumAryabhatta Research Institute of Observational Sciences (ARIES) , Manora Peak, Nainital-263001, IndiaSolar Physics and Space Plasma Research Centre, School of Mathematical and Physical Sciences, University of Sheffield , Hicks Bldg, Hounsfield Road, Sheffield S1 3RH, UK; Department of Astronomy, Eötvös Lorńd University , 1/A Pázmány Péter sétány, H-1117 Budapest, Hungary; Gyula Bay Zoltán Solar Observatory (GSO) , Hungarian Solar Physics Foundation (HSPF), Petőfi tér 3., Gyula, H-5700, HungaryPlasma- β is an important fundamental physical quantity in solar plasma physics, which determines the dominating process in the solar atmosphere, i.e., magnetic or thermodynamic processes. Here, for the first time, we provide variations of magnetic field and plasma- β along magnetically structured loops from the photosphere to the corona. We have selected several fan loops rooted in sunspot umbra observed simultaneously by the Interface Region Imaging Spectrograph and Solar Dynamics Observatory. The 3 minute slow waves enabled us to trace and analyze several fan loops with cross-sectional areas in the lower atmosphere and locate their footpoints at the photosphere. We find the rms magnetic field strengths in the range 1596–2269 G at the photospheric footpoints of the fan loops, which decrease rapidly to 158–236 G at the coronal footpoints. We estimated the plasma- β at the photospheric and coronal footpoints in the range 0.2–0.5 and 0.0001–0.001, respectively. We found plasma- β < 1 along the whole loop, whereas the plasma- β ≈ 1 layer is found to be at subphotospheric heights. We compared our findings for isolated individual fan loops with a previously established model for active regions and found an almost similar pattern in variations with height, but with different plasma- β values. Our results demonstrate the seismological potential of 3 minute slow waves omnipresent in the umbral sunspot atmosphere to probe and map isolated loops and determine magnetic field and plasma- β along these loops. The obtained parameters provide crucial ingredients for the theoretical modeling of the umbral atmosphere and wave dynamics along loops.https://doi.org/10.3847/2041-8213/ade9beSolar atmosphereSunspotsSolar coronal loopsMagnetohydrodynamicsSolar magnetic fields
spellingShingle Ananya Rawat
Girjesh Gupta
Tom Van Doorsselaere
S. Krishna Prasad
Robertus Erdélyi
Understanding the Magnetic Field and Plasma-β along Umbral Fan Loops Traced Using 3 Minute Slow Waves
The Astrophysical Journal Letters
Solar atmosphere
Sunspots
Solar coronal loops
Magnetohydrodynamics
Solar magnetic fields
title Understanding the Magnetic Field and Plasma-β along Umbral Fan Loops Traced Using 3 Minute Slow Waves
title_full Understanding the Magnetic Field and Plasma-β along Umbral Fan Loops Traced Using 3 Minute Slow Waves
title_fullStr Understanding the Magnetic Field and Plasma-β along Umbral Fan Loops Traced Using 3 Minute Slow Waves
title_full_unstemmed Understanding the Magnetic Field and Plasma-β along Umbral Fan Loops Traced Using 3 Minute Slow Waves
title_short Understanding the Magnetic Field and Plasma-β along Umbral Fan Loops Traced Using 3 Minute Slow Waves
title_sort understanding the magnetic field and plasma β along umbral fan loops traced using 3 minute slow waves
topic Solar atmosphere
Sunspots
Solar coronal loops
Magnetohydrodynamics
Solar magnetic fields
url https://doi.org/10.3847/2041-8213/ade9be
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