Solar coronal magnetic fields derived using seismology techniques applied to omnipresent sunspot waves

David B. Jess, Veronika E. Reznikova, Robert S. I. Ryans, Damian J. Christian, Peter H. Keys, Michail Mathioudakis, Duncan H. MacKay, S. Krishna Prasad, Dipankar Banerjee, Samuel D. T. Grant, Sean Yau, Conor Diamond

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Abstract

Sunspots on the surface of the Sun are the observational signatures of intense manifestations of tightly packed magnetic field lines, with near-vertical field strengths exceeding 6,000 G in extreme cases1. It is well accepted that both the plasma density and the magnitude of the magnetic field strength decrease rapidly away from the solar surface, making high-cadence coronal measurements through traditional Zeeman and Hanle effects difficult as the observational signatures are fraught with low-amplitude signals that can become swamped with instrumental noise2, 3. Magneto-hydrodynamic (MHD) techniques have previously been applied to coronal structures, with single and spatially isolated magnetic field strengths estimated as 9–55 G (refs 4,5,6,7). A drawback with previous MHD approaches is that they rely on particular wave modes alongside the detectability of harmonic overtones. Here we show, for the first time, how omnipresent magneto-acoustic waves, originating from within the underlying sunspot and propagating radially outwards, allow the spatial variation of the local coronal magnetic field to be mapped with high precision. We find coronal magnetic field strengths of 32 ± 5 G above the sunspot, which decrease rapidly to values of approximately 1 G over a lateral distance of 7,000 km, consistent with previous isolated and unresolved estimations. Our results demonstrate a new, powerful technique that harnesses the omnipresent nature of sunspot oscillations to provide magnetic field mapping capabilities close to a magnetic source in the solar corona.
Original languageEnglish
Pages (from-to)179-185
Number of pages7
JournalNature Physics
Volume12
Early online date16 Nov 2015
DOIs
Publication statusPublished - 2016

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seismology
sunspots
field strength
magnetic fields
hydrodynamics
signatures
harmonics
harnesses
Zeeman effect
solar corona
plasma density
sun
oscillations
acoustics

Cite this

Jess, David B. ; Reznikova, Veronika E. ; Ryans, Robert S. I. ; Christian, Damian J. ; Keys, Peter H. ; Mathioudakis, Michail ; MacKay, Duncan H. ; Prasad, S. Krishna ; Banerjee, Dipankar ; Grant, Samuel D. T. ; Yau, Sean ; Diamond, Conor. / Solar coronal magnetic fields derived using seismology techniques applied to omnipresent sunspot waves. In: Nature Physics. 2016 ; Vol. 12. pp. 179-185.
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title = "Solar coronal magnetic fields derived using seismology techniques applied to omnipresent sunspot waves",
abstract = "Sunspots on the surface of the Sun are the observational signatures of intense manifestations of tightly packed magnetic field lines, with near-vertical field strengths exceeding 6,000 G in extreme cases1. It is well accepted that both the plasma density and the magnitude of the magnetic field strength decrease rapidly away from the solar surface, making high-cadence coronal measurements through traditional Zeeman and Hanle effects difficult as the observational signatures are fraught with low-amplitude signals that can become swamped with instrumental noise2, 3. Magneto-hydrodynamic (MHD) techniques have previously been applied to coronal structures, with single and spatially isolated magnetic field strengths estimated as 9–55 G (refs 4,5,6,7). A drawback with previous MHD approaches is that they rely on particular wave modes alongside the detectability of harmonic overtones. Here we show, for the first time, how omnipresent magneto-acoustic waves, originating from within the underlying sunspot and propagating radially outwards, allow the spatial variation of the local coronal magnetic field to be mapped with high precision. We find coronal magnetic field strengths of 32 ± 5 G above the sunspot, which decrease rapidly to values of approximately 1 G over a lateral distance of 7,000 km, consistent with previous isolated and unresolved estimations. Our results demonstrate a new, powerful technique that harnesses the omnipresent nature of sunspot oscillations to provide magnetic field mapping capabilities close to a magnetic source in the solar corona.",
author = "Jess, {David B.} and Reznikova, {Veronika E.} and Ryans, {Robert S. I.} and Christian, {Damian J.} and Keys, {Peter H.} and Michail Mathioudakis and MacKay, {Duncan H.} and Prasad, {S. Krishna} and Dipankar Banerjee and Grant, {Samuel D. T.} and Sean Yau and Conor Diamond",
year = "2016",
doi = "10.1038/nphys3544",
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volume = "12",
pages = "179--185",
journal = "Nature Physics",
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Jess, DB, Reznikova, VE, Ryans, RSI, Christian, DJ, Keys, PH, Mathioudakis, M, MacKay, DH, Prasad, SK, Banerjee, D, Grant, SDT, Yau, S & Diamond, C 2016, 'Solar coronal magnetic fields derived using seismology techniques applied to omnipresent sunspot waves', Nature Physics, vol. 12, pp. 179-185. https://doi.org/10.1038/nphys3544

Solar coronal magnetic fields derived using seismology techniques applied to omnipresent sunspot waves. / Jess, David B.; Reznikova, Veronika E. ; Ryans, Robert S. I.; Christian, Damian J.; Keys, Peter H.; Mathioudakis, Michail; MacKay, Duncan H.; Prasad, S. Krishna; Banerjee, Dipankar; Grant, Samuel D. T.; Yau, Sean; Diamond, Conor.

In: Nature Physics, Vol. 12, 2016, p. 179-185.

Research output: Contribution to journalLetter

TY - JOUR

T1 - Solar coronal magnetic fields derived using seismology techniques applied to omnipresent sunspot waves

AU - Jess, David B.

AU - Reznikova, Veronika E.

AU - Ryans, Robert S. I.

AU - Christian, Damian J.

AU - Keys, Peter H.

AU - Mathioudakis, Michail

AU - MacKay, Duncan H.

AU - Prasad, S. Krishna

AU - Banerjee, Dipankar

AU - Grant, Samuel D. T.

AU - Yau, Sean

AU - Diamond, Conor

PY - 2016

Y1 - 2016

N2 - Sunspots on the surface of the Sun are the observational signatures of intense manifestations of tightly packed magnetic field lines, with near-vertical field strengths exceeding 6,000 G in extreme cases1. It is well accepted that both the plasma density and the magnitude of the magnetic field strength decrease rapidly away from the solar surface, making high-cadence coronal measurements through traditional Zeeman and Hanle effects difficult as the observational signatures are fraught with low-amplitude signals that can become swamped with instrumental noise2, 3. Magneto-hydrodynamic (MHD) techniques have previously been applied to coronal structures, with single and spatially isolated magnetic field strengths estimated as 9–55 G (refs 4,5,6,7). A drawback with previous MHD approaches is that they rely on particular wave modes alongside the detectability of harmonic overtones. Here we show, for the first time, how omnipresent magneto-acoustic waves, originating from within the underlying sunspot and propagating radially outwards, allow the spatial variation of the local coronal magnetic field to be mapped with high precision. We find coronal magnetic field strengths of 32 ± 5 G above the sunspot, which decrease rapidly to values of approximately 1 G over a lateral distance of 7,000 km, consistent with previous isolated and unresolved estimations. Our results demonstrate a new, powerful technique that harnesses the omnipresent nature of sunspot oscillations to provide magnetic field mapping capabilities close to a magnetic source in the solar corona.

AB - Sunspots on the surface of the Sun are the observational signatures of intense manifestations of tightly packed magnetic field lines, with near-vertical field strengths exceeding 6,000 G in extreme cases1. It is well accepted that both the plasma density and the magnitude of the magnetic field strength decrease rapidly away from the solar surface, making high-cadence coronal measurements through traditional Zeeman and Hanle effects difficult as the observational signatures are fraught with low-amplitude signals that can become swamped with instrumental noise2, 3. Magneto-hydrodynamic (MHD) techniques have previously been applied to coronal structures, with single and spatially isolated magnetic field strengths estimated as 9–55 G (refs 4,5,6,7). A drawback with previous MHD approaches is that they rely on particular wave modes alongside the detectability of harmonic overtones. Here we show, for the first time, how omnipresent magneto-acoustic waves, originating from within the underlying sunspot and propagating radially outwards, allow the spatial variation of the local coronal magnetic field to be mapped with high precision. We find coronal magnetic field strengths of 32 ± 5 G above the sunspot, which decrease rapidly to values of approximately 1 G over a lateral distance of 7,000 km, consistent with previous isolated and unresolved estimations. Our results demonstrate a new, powerful technique that harnesses the omnipresent nature of sunspot oscillations to provide magnetic field mapping capabilities close to a magnetic source in the solar corona.

U2 - 10.1038/nphys3544

DO - 10.1038/nphys3544

M3 - Letter

VL - 12

SP - 179

EP - 185

JO - Nature Physics

JF - Nature Physics

SN - 1745-2473

ER -