A Magnetogram-matching Method for Energizing Magnetic Flux Ropes Toward Eruption. (arXiv:2205.03982v2 [astro-ph.SR] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Titov_V/0/1/0/all/0/1">Viacheslav S. Titov</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Downs_C/0/1/0/all/0/1">Cooper Downs</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Torok_T/0/1/0/all/0/1">Tibor Török</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Linker_J/0/1/0/all/0/1">Jon A. Linker</a> (1) ((1) Predictive Science Inc., San Diego, CA, USA)
We propose a new “helicity-pumping” method for energizing coronal equilibria
that contain a magnetic flux rope (MFR) toward an eruption. We achieve this in
a sequence of MHD relaxations of small line-tied pulses of magnetic helicity,
each of which is simulated by a suitable rescaling of the current-carrying part
of the field. The whole procedure is “magnetogram-matching” because it involves
no changes to the normal component of the field at the photospheric boundary.
The method is illustrated by applying it to an observed force-free
configuration whose MFR is modeled with our regularized Biot-Savart law method.
We find that, in spite of the bipolar character of the external field, the MFR
eruption is sustained by two reconnection processes. The first, which we refer
to as breakthrough reconnection, is analogous to breakout reconnection in
quadrupolar configurations. It occurs at a quasi-separator inside a current
layer that wraps around the erupting MFR and is caused by the photospheric
line-tying effect. The second process is the classical tether-cutting
reconnection, which develops at the second quasi-separator inside a vertical
current layer that is formed below the erupting MFR. Both reconnection
processes work in tandem with the magnetic forces of the unstable MFR to propel
it through the overlying ambient field, and their interplay may also be
relevant for the thermal processes occurring in the plasma of solar flares. The
considered example suggests that our method will be beneficial for both the
modeling of observed eruptive events and theoretical studies of eruptions in
idealized magnetic configurations.
We propose a new “helicity-pumping” method for energizing coronal equilibria
that contain a magnetic flux rope (MFR) toward an eruption. We achieve this in
a sequence of MHD relaxations of small line-tied pulses of magnetic helicity,
each of which is simulated by a suitable rescaling of the current-carrying part
of the field. The whole procedure is “magnetogram-matching” because it involves
no changes to the normal component of the field at the photospheric boundary.
The method is illustrated by applying it to an observed force-free
configuration whose MFR is modeled with our regularized Biot-Savart law method.
We find that, in spite of the bipolar character of the external field, the MFR
eruption is sustained by two reconnection processes. The first, which we refer
to as breakthrough reconnection, is analogous to breakout reconnection in
quadrupolar configurations. It occurs at a quasi-separator inside a current
layer that wraps around the erupting MFR and is caused by the photospheric
line-tying effect. The second process is the classical tether-cutting
reconnection, which develops at the second quasi-separator inside a vertical
current layer that is formed below the erupting MFR. Both reconnection
processes work in tandem with the magnetic forces of the unstable MFR to propel
it through the overlying ambient field, and their interplay may also be
relevant for the thermal processes occurring in the plasma of solar flares. The
considered example suggests that our method will be beneficial for both the
modeling of observed eruptive events and theoretical studies of eruptions in
idealized magnetic configurations.
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