Solar Magnetic Tracking. II. The Apparent Unipolar Origin of Quiet‐Sun Flux

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Abstract

We investigate the origin of small-scale flux concentrations in the quiet Sun. In apparent violation of the physical requirement for flux balance, 94% of the features containing newly detected flux are unipolar at a resolution of 1.2''. We analyze 2619 of these apparent unipolar emergences in an image sequence from the SOHO MDI magnetograph and compare the ensemble average to a model of asymmetric bipolar emergence that could in principle hide opposing flux under the noise floor of MDI. We examine the statistical consequences of this mechanism and find that it cannot be responsible for more than a small fraction of the unipolar emergences. We conclude that the majority of the newly detected flux in the quiet Sun is instead due to the coalescence of previously existing but unresolved flux into concentrations that are large and strong enough to be detected. We estimate the rate of coalescence into arcsecond-scale magnetic features averaged over the solar surface to be 7 × 1021 Mx hr−1, comparable to the reported flux injection rate due to ephemeral regions. This implies that most flux in the solar network has been processed by very small scale shredding, emergence, cancellation, and/or coalescence that is not resolved at 1.2'', and it suggests that currently unresolved emergences may be at least as important as ephemeral region emergences to the overall flux budget.

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