The Magnetic Origin of Solar Campfires. (arXiv:2110.06846v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Panesar_N/0/1/0/all/0/1">Navdeep K. Panesar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tiwari_S/0/1/0/all/0/1">Sanjiv K. Tiwari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Berghmans_D/0/1/0/all/0/1">David Berghmans</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cheung_M/0/1/0/all/0/1">Mark C. M. Cheung</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Muller_D/0/1/0/all/0/1">Daniel Muller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Auchere_F/0/1/0/all/0/1">Frederic Auchere</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhukov_A/0/1/0/all/0/1">Andrei Zhukov</a>

Solar campfires are fine-scale heating events, recently observed by Extreme
Ultraviolet Imager (EUI), onboard Solar Orbiter. Here we use EUI 174AA
images, together with EUV images from SDO/AIA, and line-of-sight magnetograms
from SDO/HMI to investigate the magnetic origin of 52 randomly selected
campfires in the quiet solar corona. We find that (i) the campfires are rooted
at the edges of photospheric magnetic network lanes; (ii) most of the campfires
reside above the neutral line between majority-polarity magnetic flux patch and
a merging minority-polarity flux patch, with a flux cancelation rate of
$sim$10$^{18}$Mx hr$^{-1}$; (iii) some of the campfires occur repeatedly from
the same neutral line; (iv) in the large majority of instances, campfires are
preceded by a cool-plasma structure, analogous to minifilaments in coronal
jets; and (v) although many campfires have `complex’ structure, most campfires
resemble small-scale jets, dots, or loops. Thus, `campfire’ is a general term
that includes different types of small-scale solar dynamic features. They
contain sufficient magnetic energy ($sim$10$^{26}$-10$^{27}$ erg) to heat the
solar atmosphere locally to 0.5–2.5MK. Their lifetimes range from about a
minute to over an hour, with most of the campfires having a lifetime of $<$10
minutes. The average lengths and widths of the campfires are 5400$pm$2500km
and 1600$pm$640km, respectively. Our observations suggest that (a) the
presence of magnetic flux ropes may be ubiquitous in the solar atmosphere and
not limited to coronal jets and larger-scale eruptions that make CMEs, and (b)
magnetic flux cancelation is the fundamental process for the formation and
triggering of most campfires.

Solar campfires are fine-scale heating events, recently observed by Extreme
Ultraviolet Imager (EUI), onboard Solar Orbiter. Here we use EUI 174AA
images, together with EUV images from SDO/AIA, and line-of-sight magnetograms
from SDO/HMI to investigate the magnetic origin of 52 randomly selected
campfires in the quiet solar corona. We find that (i) the campfires are rooted
at the edges of photospheric magnetic network lanes; (ii) most of the campfires
reside above the neutral line between majority-polarity magnetic flux patch and
a merging minority-polarity flux patch, with a flux cancelation rate of
$sim$10$^{18}$Mx hr$^{-1}$; (iii) some of the campfires occur repeatedly from
the same neutral line; (iv) in the large majority of instances, campfires are
preceded by a cool-plasma structure, analogous to minifilaments in coronal
jets; and (v) although many campfires have `complex’ structure, most campfires
resemble small-scale jets, dots, or loops. Thus, `campfire’ is a general term
that includes different types of small-scale solar dynamic features. They
contain sufficient magnetic energy ($sim$10$^{26}$-10$^{27}$ erg) to heat the
solar atmosphere locally to 0.5–2.5MK. Their lifetimes range from about a
minute to over an hour, with most of the campfires having a lifetime of $<$10
minutes. The average lengths and widths of the campfires are 5400$pm$2500km
and 1600$pm$640km, respectively. Our observations suggest that (a) the
presence of magnetic flux ropes may be ubiquitous in the solar atmosphere and
not limited to coronal jets and larger-scale eruptions that make CMEs, and (b)
magnetic flux cancelation is the fundamental process for the formation and
triggering of most campfires.

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