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Title: THE UBIQUITOUS PRESENCE OF LOOPLIKE FINE STRUCTURE INSIDE SOLAR ACTIVE REGIONS

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.
Authors:
 [1]
  1. Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)
Publication Date:
OSTI Identifier:
22518571
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 820; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CHROMOSPHERE; CONCENTRATION RATIO; ELEMENT ABUNDANCE; EXTREME ULTRAVIOLET RADIATION; FACULAE; FINE STRUCTURE; HEATING; IMAGES; IRON IONS; MAGNETIC FIELDS; MAGNETIC FLUX; SUN; SURFACES