Bibcode
Khomenko, E.; Díaz, A. J.; de Vicente, A.; Collados, M.; Luna, M.
Bibliographical reference
Astronomy and Astrophysics, Volume 565, id.A45, 15 pp.
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5
2014
Journal
Citations
59
Refereed citations
58
Description
We study the Rayleigh-Taylor instability (RTI) at a prominence-corona
transition region in a non-linear regime. Our aim is to understand how
the presence of neutral atoms in the prominence plasma influences the
instability growth rate, as well as the evolution of velocity, magnetic
field vector, and thermodynamic parameters of turbulent drops. We
perform 2.5D numerical simulations of the instability initiated by a
multi-mode perturbation at the corona-prominence interface using a
single-fluid magnetohydrodynamic (MHD) approach including a generalized
Ohm's law. The initial equilibrium configuration is purely hydrostatic
and contains a homogeneous horizontal magnetic field forming an angle
with the direction in which the plasma is perturbed. We analyze
simulations with two different orientations of the magnetic field. For
each field orientation we compare two simulations, one for the pure MHD
case, and one including the ambipolar diffusion in Ohm's law (AD case).
Other than that, both simulations for each field orientation are
identical. The numerical results in the initial stage of the instability
are compared with the analytical linear calculations. We find that the
configuration is always unstable in the AD case. The growth rate of the
small-scale modes in the non-linear regime is up to 50% larger in the AD
case than in the purely MHD case and the average velocities of flows are
a few percentage points higher. Significant drift momenta are found at
the interface between the coronal and the prominence material at all
stages of the instability, produced by the faster downward motion of the
neutral component with respect to the ionized component. The differences
in temperature of the bubbles between the ideal and non-ideal case are
also significant, reaching 30%. There is an asymmetry between large
rising bubbles and small-scale down flowing fingers, favoring the
detection of upward velocities in observations.
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