[Loops] New paper: "The ubiquitous presence of looplike fine structure inside solar active regions", by Wang, Y.-M.

[Ignacio Ugarte-Urra]

Dear all,

Here is a paper that Yi-Ming Wang has asked me to send for him. He’s not a member of the mailing list yet.

Best regards,
Ignacio


http://iopscience.iop.org/article/10.3847/2041-8205/820/1/L13 <http://iopscience.iop.org/article/10.3847/2041-8205/820/1/L13>

"THE UBIQUITOUS PRESENCE OF LOOPLIKE FINE STRUCTURE INSIDE SOLAR ACTIVE REGIONS"
Y.-M. Wang

Abstract
Although most of the solar surface outside active regions (ARs) is pervaded by small-scale fields of mixed polarity, this magnetic "carpet" or "junkyard" is thought to be largely absent inside AR plages and strong network. However, using extreme-ultraviolet images and line-of-sight magnetograms from the Solar Dynamics Observatory, we find that unipolar flux concentrations, both inside and outside ARs, often have small, loop-shaped Fe ix 17.1 and Fe xii 19.3 nm features embedded within them, even though no minority-polarity flux is visible in the corresponding magnetograms. Such looplike structures, characterized by horizontal sizes of ~3–5 Mm and varying on timescales of minutes or less, are seen inside bright 17.1 nm moss, as well as in fainter moss-like regions associated with weaker network outside ARs. We also note a tendency for bright coronal loops to show compact, looplike features at their footpoints. Based on these observations, we suggest that present-day magnetograms may be substantially underrepresenting the amount of minority-polarity flux inside plages and strong network, and that reconnection between small bipoles and the overlying large-scale field could be a major source of coronal heating both in ARs and in the quiet Sun.
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