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Abstract:

In order to test different models of coronal heating, we have investigated how the magnetic field strength of coronal flux tubes depends on the end-to-end length of the tube. Using photospheric magnetograms from both observed and idealized active regions, we computed potential, linear force-free, and magnetostatic extrapolation models. For each model, we then determined the average coronal field strength, 〈B〉, in approximately 1000 individual flux tubes with regularly spaced footpoints. Scatter plots of 〈B〉; versus length, L, are characterized by a flat section for small L and a steeply declining section for large L. They are well described by a function of the form log 〈B〉 = C1 + C2 log L + C3/2 log (L2 + S2), where C2 ≈ 0, - 3 ≤ C3 ≤ - 1, and 40 ≤ S ≤ 240 Mm is related to the characteristic size of the active region. There is a tendency for the magnitude of C3 to decrease as the magnetic complexity of the region increases. The average magnetic energy in a flux tube, 〈B;2〉, exhibits a similar behavior, with only C3 being significantly different. For flux tubes of intermediate length, 50 ≤ L ≤ 300 Mm, corresponding to the soft X-ray loops in a study by Klimchuk & Porter (1995), we find a universal scaling law of the form 〈B〉 ∞ Lδ, where δ = -0.88 ± 0.3. By combining this with the Klimchuk & Porter result that the heating rate scales as L-2, we can test different models of coronal heating. We find that models involving the gradual stressing of the magnetic field, by slow footpoint motions, are in generally better agreement with the observational constraints than are wave heating models. We conclude, however, that the theoretical models must be more fully developed and the observational uncertainties must be reduced before any definitive statements about specific heating mechanisms can be made.

Registro:

Documento: Artículo
Título:Magnetic field and plasma scaling laws: Their implications for coronal heating models
Autor:Mandrini, C.H.; Démoulin, P.; Klimchuk, J.A.
Filiación:Inst. Astronomia Fisica del Espacio, IAFE, CC. 67 Suc. 28, 1428 Buenos Aires, Argentina
Observatoire de Paris, Section Meudon, URA 2080 (CNRS), F-92195 Meudon Principal Cedex, France
Naval Research Laboratory, Washington, DC 20375-5352, United States
Palabras clave:Sun: corona; Sun: magnetic fields; Sun: X-rays, gamma rays
Año:2000
Volumen:530
Número:2 PART 1
Página de inicio:999
Página de fin:1015
Título revista:Astrophysical Journal
Título revista abreviado:Astrophys. J.
ISSN:0004637X
Registro:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v530_n2PART1_p999_Mandrini

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Citas:

---------- APA ----------
Mandrini, C.H., Démoulin, P. & Klimchuk, J.A. (2000) . Magnetic field and plasma scaling laws: Their implications for coronal heating models. Astrophysical Journal, 530(2 PART 1), 999-1015.
Recuperado de https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v530_n2PART1_p999_Mandrini [ ]
---------- CHICAGO ----------
Mandrini, C.H., Démoulin, P., Klimchuk, J.A. "Magnetic field and plasma scaling laws: Their implications for coronal heating models" . Astrophysical Journal 530, no. 2 PART 1 (2000) : 999-1015.
Recuperado de https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v530_n2PART1_p999_Mandrini [ ]
---------- MLA ----------
Mandrini, C.H., Démoulin, P., Klimchuk, J.A. "Magnetic field and plasma scaling laws: Their implications for coronal heating models" . Astrophysical Journal, vol. 530, no. 2 PART 1, 2000, pp. 999-1015.
Recuperado de https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v530_n2PART1_p999_Mandrini [ ]
---------- VANCOUVER ----------
Mandrini, C.H., Démoulin, P., Klimchuk, J.A. Magnetic field and plasma scaling laws: Their implications for coronal heating models. Astrophys. J. 2000;530(2 PART 1):999-1015.
Available from: https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v530_n2PART1_p999_Mandrini [ ]