Magnetic Flux in the Solar Convective Envelope Inferred from Initial Observations of Sunspots

Different life spans of sunspots suggest their origin at different depths, and by measuring magnetic fluxes from their first observation on the surface, one can estimate the strength of magnetic flux at different anchoring depths. From SOHO MDI magnetograms, we infer the strength of magnetic flux an...

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Veröffentlicht in:The Astrophysical journal 2007-09, Vol.667 (1), p.585-590
Hauptverfasser: Hiremath, K. M, Lovely, M. R
Format: Artikel
Sprache:eng
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Zusammenfassung:Different life spans of sunspots suggest their origin at different depths, and by measuring magnetic fluxes from their first observation on the surface, one can estimate the strength of magnetic flux at different anchoring depths. From SOHO MDI magnetograms, we infer the strength of magnetic flux and rate of emergence of magnetic flux at different anchoring depths in the solar convective envelope by measuring initial magnetic fluxes of the well-developed sunspots on the surface. Important findings are: (1) the majority of the spot groups that have first observation on the surface are bipolar; (2) Irrespective of their sizes, the bipolar spots with different life spans have average magnetic field strengths of similar to 500 G during their first observation; (3) the average field strength at the site of anchoring depths of the sunspots is estimated to be similar to 10 super(6) G near the base of the convectlve envelope and similar to 10 super(4) G near the surface; (4) the dynamo-a source of sunspot activity-is distributed throughout the convectlve envelope; and (5) the rate of emergence of initial magnetic flux of such a distributed dynamo near the base of the convection zone is similar to 6 x 10 super(10) Mx day super(-1) and is 40% higher than the rate of emergence of initial magnetic flux near the surface.
ISSN:0004-637X
1538-4357
DOI:10.1086/520842