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Titolo:
Eigenmode approach to coronal magnetic structure with differential solar rotation
Autore:
Schulz, M;
Indirizzi:
Lockhead Martin Adv Technol Ctr, Space Phys Dept, Palo Alto, CA 94304 USA Lockhead Martin Adv Technol Ctr Palo Alto CA USA 94304 Alto, CA 94304 USA
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
fascicolo: A8, volume: 106, anno: 2001,
pagine: 15859 - 15867
SICI:
0148-0227(20010801)106:A8<15859:EATCMS>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
HELIOSPHERIC CURRENT SHEET; SUNSPOT CYCLE-21; RIGID ROTATION; FIELD; EVOLUTION; HOLES; SUN; FLUX;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
30
Recensione:
Indirizzi per estratti:
Indirizzo: Schulz, M Lockhead Martin Adv Technol Ctr, Space Phys Dept, L9-42,Bldg 255,3251 Hanover St, Palo Alto, CA 94304 USA Lockhead Martin Adv Technol Ctr L9-42,Bldg 255,3251 Hanover St Palo Alto CA USA 94304
Citazione:
M. Schulz, "Eigenmode approach to coronal magnetic structure with differential solar rotation", J GEO R-S P, 106(A8), 2001, pp. 15859-15867

Abstract

Diffusion of field line foot points in the photosphere couples with latitude-dependent solar rotation to define an eigenvalue problem, such that coronal magnetic structures derived from certain specific linear combinations of spherical harmonic functions are found to rotate rigidly about the Sun. Such eigenmodes and their corresponding complex eigenfrequencies are readilyidentified by diagonalizing progressively larger matrix representations ofthe eigenvalue problem. For azimuthal harmonic number m = 1, the eigenvalue with the least negative imaginary part (approximate to - 0.6 year(-1) forfootpoint diffusion coefficient D-perpendicular to = 600 km(2)s(-1) and otherwise roughly proportional to D-perpendicular to(1/2)) corresponds to an eigenmode whose main component is the dipole (n = 1) moment perpendicular to the Sun's rotation axis. Associated values of Re omega (1)(1) correspond to heliomagnetic rotation at 99.4% of the Sun's equatorial rate for D-perpendicular to = 600 km(2)s(-1) and otherwise to a retrograde deviation roughly proportional to D-perpendicular to(1/2) from the Sun's equatorial rotation rate. This eigenmode corresponds to the almost rigidly rotating coronal structure found by Wang et al. [1988] in their numerical simulations of the coronal magnetic field. The associated heliospheric current sheet rotates almost rigidly about the Sun despite the anchorage of adjacent field lines in a differentially rotating photosphere. This particular eigenmode also corresponds most nearly to the nonaxial part of the tilted dipole in the heliospheric model of Fisk [1996], whereby differential solar rotation leads to a latitudinal circulation of field lines through the heliosphere and thus to large-scale heliospheric convection.

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Documento generato il 11/07/20 alle ore 11:01:40