Observational Study of Large Amplitude Longitudinal Oscillations in a Solar Filament

AbstractOn 20 August 2010 an energetic disturbance triggered damped large-amplitude longitudinal (LAL) oscillations in almost an entire filament. In the present work we analyze this periodic motion in the filament to characterize the damping and restoring mechanism of the oscillation. Our method involves placing slits along the axis of the filament at different angles with respect to the spine of the filament, finding the angle at which the oscillation is clearest, and fitting the resulting oscillation pattern to decaying sinusoidal and Bessel functions. These functions represent the equations of motion of a pendulum damped by mass accretion. With this method we determine the period and the decaying time of the oscillation. Our preliminary results support the theory presented by Luna and Karpen (2012) that the restoring force of LAL oscillations is solar gravity in the tubes where the threads oscillate, and the damping mechanism is the ongoing accumulation of mass onto the oscillating threads. Following an earlier paper, we have determined the magnitude and radius of curvature of the dipped magnetic flux tubes hosting a thread along the filament, as well as the mass accretion rate of the filament threads, via the fitted parameters.

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Large-amplitude longitudinal oscillations in solar prominences

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313010909 ◽

2013 ◽

Vol 8 (S300) ◽

pp. 155-158

Author(s):

Manuel Luna ◽

Judith Karpen ◽

Antonio Díaz ◽

Kalman Knizhnik ◽

Karin Muglach ◽

...

Keyword(s):

Large Amplitude ◽

Coronal Magnetic Field ◽

Tube Length ◽

Radius Of Curvature ◽

Restoring Force ◽

Flux Tubes ◽

Filament Axis ◽

Solar Prominences ◽

Class Flare ◽

Strongly Damped

AbstractLarge-amplitude longitudinal (LAL) prominence oscillations consist of periodic mass motions along a filament axis. The oscillations appear to be triggered by an energetic event, such as a microflare, subflare, or small C-class flare, close to one end of the filament. Observations reveal speeds of several tens to 100 km/s, periods of order 1 hr, damping times of a few periods, and displacements equal to a significant fraction of the prominence length. We have developed a theoretical model to explain the restoring force and the damping mechanism. Our model demonstrates that the main restoring force is the projected gravity in the flux tube dips where the threads oscillate. Although the period is independent of the tube length and the constantly growing mass, the motions are strongly damped by the steady accretion of mass onto the threads. We conclude that the LAL movements represent a collective oscillation of a large number of cool, dense threads moving along dipped flux tubes, triggered by a nearby energetic event. Our model yields a powerful seismological method for constraining the coronal magnetic field strength and radius of curvature at the thread locations.

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Nonlinear fast sausage waves in homogeneous magnetic flux tubes

Journal of Plasma Physics ◽

10.1017/s002237781500135x ◽

2015 ◽

Vol 81 (6) ◽

Cited By ~ 3

Author(s):

Badma B. Mikhalyaev ◽

Michael S. Ruderman

Keyword(s):

Bessel Functions ◽

Nonlinear Evolution ◽

Solar Physics ◽

Modified Bessel Functions ◽

Magnetohydrodynamic Equations ◽

Carrier Wave ◽

Flux Tubes ◽

Magnetic Flux Tubes ◽

Ideal Magnetohydrodynamic ◽

The Ideal

We consider fast sausage waves in straight homogeneous magnetic tubes. The plasma motion is described by the ideal magnetohydrodynamic equations in the cold plasma approximation. We derive the nonlinear Schrödinger equation describing the nonlinear evolution of an envelope of a carrier wave. The coefficients of this equation are expressed in terms Bessel and modified Bessel functions. They are calculated numerically for various values of parameters. In particular, we show that the criterion for the onset of the modulational or Benjamin–Fair instability is satisfied. The implication of the obtained results for solar physics is discussed.

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Linear Visco-Resistive Computations of Magnetohydrodynamic Waves: I. The Code and Test Cases

International Astronomical Union Colloquium ◽

10.1017/s0252921100025926 ◽

1994 ◽

Vol 144 ◽

pp. 503-505

Author(s):

R. Erdélyi ◽

M. Goossens ◽

S. Poedts

Keyword(s):

Resonant Absorption ◽

Numerical Code ◽

Mhd Waves ◽

Test Cases ◽

Numerical Accuracy ◽

Element Discretization ◽

Flux Tubes ◽

Magnetohydrodynamic Waves ◽

Viscosity Coefficients ◽

Magnetic Flux Tubes

AbstractThe stationary state of resonant absorption of linear, MHD waves in cylindrical magnetic flux tubes is studied in viscous, compressible MHD with a numerical code using finite element discretization. The full viscosity tensor with the five viscosity coefficients as given by Braginskii is included in the analysis. Our computations reproduce the absorption rates obtained by Lou in scalar viscous MHD and Goossens and Poedts in resistive MHD, which guarantee the numerical accuracy of the tensorial viscous MHD code.

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Resonant Instability of Kink Oscillations in Magnetic Flux Tubes with Siphon Flow

Solar Physics ◽

10.1007/s11207-021-01842-0 ◽

2021 ◽

Vol 296 (6) ◽

Author(s):

Michael S. Ruderman ◽

Nikolai S. Petrukhin

Keyword(s):

Flow Velocity ◽

Resonant Absorption ◽

Tube Axis ◽

Magnetic Tube ◽

Transitional Layer ◽

Threshold Velocity ◽

Flux Tubes ◽

Resonant Instability ◽

Constant Magnitude ◽

Magnetic Flux Tubes

AbstractWe study kink oscillations of a straight magnetic tube in the presence of siphon flows. The tube consists of a core and a transitional or boundary layer. The flow velocity is parallel to the tube axis, has constant magnitude, and confined in the tube core. The plasma density is constant in the tube core and it monotonically decreases in the transitional layer to its value in the surrounding plasma. We use the expression for the decrement/increment previously obtained by Ruderman and Petrukhin (Astron. Astrophys.631, A31, 2019) to study the damping and resonant instability of kink oscillations. We show that, depending on the magnitude of siphon-velocity, resonant absorption can cause either the damping of kink oscillations or their enhancement. There are two threshold velocities: When the flow velocity is below the first threshold velocity, kink oscillations damp. When the flow velocity is above the second threshold velocity, the kink oscillation amplitudes grow. Finally, when the flow velocity is between the two threshold velocities, the oscillation amplitudes do not change. We apply the theoretical result to kink oscillations of prominence threads. We show that, for particular values of thread parameters, resonant instability can excite these kink oscillations.

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Topological Transformations in Isolated Straight Magnetic Flux Tubes

The Astrophysical Journal ◽

10.1086/305740 ◽

1998 ◽

Vol 500 (2) ◽

pp. 966-977 ◽

Cited By ~ 7

Author(s):

Sergey Bazdenkov ◽

Tetsuya Sato

Keyword(s):

Magnetic Flux ◽

Flux Tubes ◽

Magnetic Flux Tubes ◽

Topological Transformations

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A Statistical Study on the Reconnection in Boundary Layers of Small-scale Magnetic Flux Tubes in Solar Winds

Chinese Astronomy and Astrophysics ◽

10.1016/j.chinastron.2013.04.005 ◽

2013 ◽

Vol 37 (2) ◽

pp. 163-174

Author(s):

Qi Yu ◽

Yao Shuo ◽

He Jian-sen ◽

Tian Hui ◽

Tu Chuan-yi

Keyword(s):

Magnetic Flux ◽

Boundary Layers ◽

Statistical Study ◽

Small Scale ◽

Flux Tubes ◽

Solar Winds ◽

Magnetic Flux Tubes

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The Influence of Binarity on Stellar Activity

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307004425 ◽

2006 ◽

Vol 2 (S240) ◽

pp. 442-452 ◽

Cited By ~ 1

Author(s):

Katalin Oláh

Keyword(s):

Binary Systems ◽

Magnetic Energy ◽

Theoretical Calculations ◽

Deep Convection ◽

Magnetic Activity ◽

Close Binary ◽

Convective Envelope ◽

Flux Tubes ◽

Gravitational Forces ◽

Magnetic Flux Tubes

AbstractActivity of late type stars is enhanced by fast rotation, which is maintained in nearly synchronized close binary systems. Magnetic activity originates in the deep convection zones of stars from where magnetic flux tubes emerge to their surfaces. The gravitational forces in binaries help the clustering of activity features giving rise to active longitudes. These preferred longitudes are observed in binaries from dwarfs to giants. Differential rotation is found in many active stars that are components of binary systems. If these binaries are circularized and nearly synchronized, then there will be a corotation latitude in their surfaces, and its position can be determined by observations and by theoretical calculations. Enhanced activity in binaries could have a reverse effect as well: strong magnetism in a binary component can modify the orbital period by the cyclic exchange of kinetic and magnetic energy in its convective envelope.

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