Large-Amplitude Longitudinal Oscillations in a Solar Filament

Luna, M.; Karpen, J. T.

doi:10.1088/2041-8205/750/1/l1

Cited by 102 publications

(112 citation statements)

References 30 publications

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“…However, here we have found that the temporal evolution of the velocity is given by the sine divided by a linear function of its argument. The phase of the argument is half that found in the case studied by Luna & Karpen (2012). The difference between the two models is in how the hot evaporated mass is deposited in the cool thread.…”

Section: Linear Theory With Strong Dampingmentioning

confidence: 76%

“…In addition, Luna & Karpen (2012) and Luna et al (2012a) assumed that the thread filled the dipped part of the flux tube A131, page 4 of 10 meaning that rθ = l p /2. Then taking into account that, for typical prominences, the density contrast is very large meaning that 1 − 1/ζ ∼ 1, we finally arrive at…”

Section: Prominence Oscillations In a Magnetic Tube With Two Straightmentioning

confidence: 99%

“…The difference between the two models is in how the hot evaporated mass is deposited in the cool thread. Luna & Karpen (2012) assumed that the hot flows adapt to the motion of the thread and accretion at both sides of the thread is symmetric. Then, the momentum transferred to the thread by the hot evaporated flows is cancelled and the net momentum transfer is zero.…”

Section: Linear Theory With Strong Dampingmentioning

confidence: 99%

“…In this article we improve the model of Luna & Karpen (2012) by considering a 1D thread model moving in a rigid magnetic tube in the presence of an accretion flow. The paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

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Damping of prominence longitudinal oscillations due to mass accretion

Luna

2016

A&A

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We study the damping of longitudinal oscillations of a prominence thread caused by the mass accretion. We suggested a simple model describing this phenomenon. In this model we considered a thin curved magnetic tube filled with the plasma. The prominence thread is in the central part of the tube and it consists of dense cold plasma. The parts of the tube at the two sides of the thread are filled with hot rarefied plasma. We assume that there are flows of rarefied plasma toward the thread caused by the plasma evaporation at the magnetic tube footpoints. Our main assumption is that the hot plasma is instantaneously accommodated by the thread when it arrives at the thread, and its temperature and density become equal to those of the thread. Then we derive the system of ordinary differential equations describing the thread dynamics. We solve this system of ordinary differential equations in two particular cases. In the first case we assume that the magnetic tube is composed of an arc of a circle with two straight lines attached to its ends such that the whole curve is smooth. A very important property of this model is that the equations describing the thread oscillations are linear for any oscillation amplitude. We obtain the analytical solution of the governing equations. Then we obtain the analytical expressions for the oscillation damping time and periods. We find that the damping time is inversely proportional to the accretion rate. The oscillation periods increase with time. We conclude that the oscillations can damp in a few periods if the inclination angle is sufficiently small, not larger that 10 • , and the flow speed is sufficiently large, not less that 30 km s −1 . In the second model we consider the tube with the shape of an arc of a circle. The thread oscillates with the pendulum frequency dependent exclusively on the radius of curvature of the arc. The damping depends on the mass accretion rate and the initial mass of the threads, that is the mass of the thread at the moment when it is perturbed. First we consider small amplitude oscillations and use the linear description. Then we consider nonlinear oscillations and assume that the damping is slow, meaning that the damping time is much larger that the characteristic oscillation time. The thread oscillations are described by the solution of the nonlinear pendulum problem with slowly varying amplitude. The nonlinearity reduces the damping time, however this reduction is small. Again the damping time is inversely proportional to the accretion rate. We also obtain that the oscillation periods decrease with time. However even for the largest initial oscillation amplitude considered in our article the period reduction does not exceed 20%. We conclude that the mass accretion can damp the motion of the threads rapidly. Thus, this mechanism can explain the observed strong damping of large-amplitude longitudinal oscillations. In addition, the damping time can be used to determine the mass accretion rate and indirectly the coronal heating.

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Section: Linear Theory With Strong Dampingmentioning

confidence: 76%

Section: Prominence Oscillations In a Magnetic Tube With Two Straightmentioning

confidence: 99%

Section: Linear Theory With Strong Dampingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Damping of prominence longitudinal oscillations due to mass accretion

Luna

2016

A&A

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“…For the extreme case of a tube with uniform cross-section, the typical distances are infinite. Figure 2 shows the fitted values of ǫ 1 and ǫ 2 for the flux tubes studied by Luna et al (2012b) and Luna & Karpen (2012).…”

Section: Flux Tube Cross-section Modelmentioning

confidence: 99%

The effects of magnetic-field geometry on longitudinal oscillations of solar prominences: Cross-sectional area variation for thin tubes

Luna

Díaz

Oliver

et al. 2016

A&A

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Context. Solar prominences are subject to both field-aligned (longitudinal) and transverse oscillatory motions, as evidenced by an increasing number of observations. Large-amplitude longitudinal motions provide valuable information on the geometry of the filamentchannel magnetic structure that supports the cool prominence plasma against gravity. Our pendulum model, in which the restoring force is the gravity projected along the dipped field lines of the magnetic structure, best explains these oscillations. However, several factors can influence the longitudinal oscillations, potentially invalidating the pendulum model. Aims. The aim of this work is to study the influence of large-scale variations in the magnetic field strength along the field lines, i.e., variations of the cross-sectional area along the flux tubes supporting prominence threads. Methods. We studied the normal modes of several flux tube configurations, using linear perturbation analysis, to assess the influence of different geometrical parameters on the oscillation properties. Results. We found that the influence of the symmetric and asymmetric expansion factors on longitudinal oscillations is small. Conclusions. We conclude that the longitudinal oscillations are not significantly influenced by variations of the cross-section of the flux tubes, validating the pendulum model in this context.

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Polarimetric Observations of the Sun

Suárez

2019

Astrophysics and Space Science Library

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Large-Amplitude Longitudinal Oscillations in a Solar Filament

Cited by 102 publications

References 30 publications

Damping of prominence longitudinal oscillations due to mass accretion

Damping of prominence longitudinal oscillations due to mass accretion

The effects of magnetic-field geometry on longitudinal oscillations of solar prominences: Cross-sectional area variation for thin tubes

Polarimetric Observations of the Sun

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