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Fine structure of solar magnetic fields

Zirin, Harold (1972) Fine structure of solar magnetic fields. Solar Physics, 22 (1). pp. 34-48. ISSN 0038-0938. doi:10.1007/bf00145459.

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The deduction of magnetic fields from chromospheric structure is extended to active regions and transverse fields. Fields independently predicted by these rules from a high resolution Hα filtergram are compared with a high resolution magnetogram. The Hα method has the advantage over conventional magnetograms that it shows transverse fields and relates the fields to the real Sun. It has the disadvantage that higher spatial resolution is required and that it is difficult and time consuming in very complicated regions. The response of the chromosphere to magnetic fields is most consistent. Vertical field is invariably marked by bright plage, with brightness roughly proportional to the field strength (except for sunspots). All dark fibrils mark transverse fields and are parallel to field lines. All polarity changes are marked by dark fibrils, which may be transverse fibrils perpendicular to the field boundary, or filaments (prominences) which connect more distant points, and in which the field lines run nearly parallel to the boundary. The asymmetry between preceding and following polarity found by Veeder and Zirin (1970) does not exist; it was due to the low resolution of the Mount Wilson magnetograms. The complexity of active region field structure depends on the history of the region; all flux erupts in simple bipolar form, and lines of force remain connected to sibling spots until reconnection takes place. Thus the complex structure only occurs after eruption of several dipoles which reconnect. The phenomenon of ‘inverted polarity’ turns out to be due to the emergence of satellite bipolar fields, where the p spot merges with the rest of the p field and the f spot appears as an included f field. Flares usually occur when the field lines from f spot reconnect from its sibling to the main spot.

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Additional Information:© 1972 Kluwer Academic Publishers. Provided by the NASA Astrophysics Data System. Received 20 July 1971; Issue Date January 1972. I am grateful to Dr J. W. Harvey and Mrs. Harvey for their magnetogram, to Dr Dale Vrabec and Dr Robert Howard for their magnetograms, and to Drs P. Foukal and S. Prata for numerous discussions. The work was supported by NSF under Grant Ga. 24015 and NASA under Grant NGL 05 002 034.
Funding AgencyGrant Number
NSFGA 24015
NASANGL 05 002 034
Subject Keywords:Flare; Fibril; Field Line; Region Field; Transverse Field
Issue or Number:1
Record Number:CaltechAUTHORS:20200630-141316969
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Official Citation:Zirin, H. Fine structure of solar magnetic fields. Sol Phys 22, 34–48 (1972).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104169
Deposited By: Tony Diaz
Deposited On:30 Jun 2020 21:24
Last Modified:16 Nov 2021 18:29

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