MODELING THE SUN'S SMALL-SCALE GLOBAL PHOTOSPHERIC MAGNETIC FIELD
ABSTRACT We present a new model for the Sun's global photospheric magnetic field during a deep minimum of activity, in which no active regions emerge. The emergence and subsequent evolution of small-scale magnetic features across the full solar surface is simulated, subject to the influence of...
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Published in | The Astrophysical journal Vol. 830; no. 2; pp. 160 - 172 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Philadelphia
The American Astronomical Society
20.10.2016
IOP Publishing |
Subjects | |
Online Access | Get full text |
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Summary: | ABSTRACT We present a new model for the Sun's global photospheric magnetic field during a deep minimum of activity, in which no active regions emerge. The emergence and subsequent evolution of small-scale magnetic features across the full solar surface is simulated, subject to the influence of a global supergranular flow pattern. Visually, the resulting simulated magnetograms reproduce the typical structure and scale observed in quiet Sun magnetograms. Quantitatively, the simulation quickly reaches a steady state, resulting in a mean field and flux distribution that are in good agreement with those determined from observations. A potential coronal magnetic field is extrapolated from the simulated full Sun magnetograms to consider the implications of such a quiet photospheric magnetic field on the corona and inner heliosphere. The bulk of the coronal magnetic field closes very low down, in short connections between small-scale features in the simulated magnetic network. Just 0.1% of the photospheric magnetic flux is found to be open at 2.5 R , around 10-100 times less than that determined for typical Helioseismic and Magnetic Imager synoptic map observations. If such conditions were to exist on the Sun, this would lead to a significantly weaker interplanetary magnetic field than is currently observed, and hence a much higher cosmic ray flux at Earth. |
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Bibliography: | ApJ101448 The Sun |
ISSN: | 0004-637X 1538-4357 |
DOI: | 10.3847/0004-637X/830/2/160 |