Significance of Cooling Effect on Comprehension of Kink Oscillations of Coronal Loops

Kink oscillations of coronal loops have been widely studied, both observationally and theoretically, over the past few decades. It has been shown that the majority of observed driven coronal loop oscillations appear to damp with either exponential or Gaussian profiles and a range of mechanisms have been proposed to account for this. However, some driven oscillations seem to evolve in manners which cannot be modeled with purely Gaussian or exponential profiles, with amplification of oscillations even being observed on occasions. Recent research has shown that incorporating the combined effects of coronal loop expansion, resonant absorption, and cooling can cause significant deviations from Gaussian and exponential profiles in damping profiles, potentially explaining increases in oscillation amplitude through time in some cases. In this article, we analyze 10 driven kink oscillations in coronal loops to further investigate the ability of expansion and cooling to explain complex damping profiles. Our results do not rely on fitting a periodicity to the oscillations meaning complexities in both temporal (period changes) and spatial (amplitude changes) can be accounted for in an elegant and simple way. Furthermore, this approach could also allow us to infer some important diagnostic information (such as, for example, the density ratio at the loop foot-points) from the oscillation profile alone, without detailed measurements of the loop and without complex numerical methods. Our results imply the existence of correlations between the density ratio at the loop foot-points and the amplitudes and periods of the oscillations. Finally, we compare our results to previous models, namely purely Gaussian and purely exponential damping profiles, through the calculation of χ2 values, finding the inclusion of cooling can produce better fits in some cases. The current study indicates that thermal evolution should be included in kink-mode oscillation models in the future to help us to better understand oscillations that are not purely Gaussian or exponential.

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Excitation and damping of disturbances in cylindrical coronal loops

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2005.1718 ◽

2005 ◽

Vol 364 (1839) ◽

pp. 547-550 ◽

Cited By ~ 7

Author(s):

Jaume Terradas ◽

Ramón Oliver ◽

José Luis Ballester

Keyword(s):

Boundary Layer ◽

Coronal Loop ◽

Normal Mode Analysis ◽

Resonant Absorption ◽

Time Dependent ◽

Mode Analysis ◽

Coronal Loops ◽

Two Dimensional ◽

Magnetohydrodynamic Equations ◽

Kink Mode

The excitation and damping of transversal coronal loop oscillations is studied using one-and two-dimensional models of line-tied cylindrical loops. By solving the time-dependent magnetohydrodynamic equations it is shown how an initial disturbance generated in the solar corona induces kink mode oscillations. We investigate the effect of the disturbance on a loop with a non-uniform boundary layer. In particular, a strong damping of transversal oscillations due to resonant absorption is found, such as predicted by previous works based on normal mode analysis.

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Weak Damping of Propagating MHD Kink Waves in the Quiescent Corona

The Astrophysical Journal ◽

10.3847/1538-4357/ac324d ◽

2021 ◽

Vol 923 (2) ◽

pp. 225

Author(s):

Richard J. Morton ◽

Ajay K. Tiwari ◽

Tom Van Doorsselaere ◽

James A. McLaughlin

Keyword(s):

Large Scale ◽

Density Ratio ◽

Resonant Absorption ◽

Coronal Plasma ◽

Energy Estimates ◽

Coronal Loops ◽

Transverse Waves ◽

Kink Mode ◽

Kink Waves ◽

The Waves

Abstract Propagating transverse waves are thought to be a key transporter of Poynting flux throughout the Sun’s atmosphere. Recent studies have shown that these transverse motions, interpreted as the magnetohydrodynamic kink mode, are prevalent throughout the corona. The associated energy estimates suggest the waves carry enough energy to meet the demands of coronal radiative losses in the quiescent Sun. However, it is still unclear how the waves deposit their energy into the coronal plasma. We present the results from a large-scale study of propagating kink waves in the quiescent corona using data from the Coronal Multi-channel Polarimeter (CoMP). The analysis reveals that the kink waves appear to be weakly damped, which would imply low rates of energy transfer from the large-scale transverse motions to smaller scales via either uniturbulence or resonant absorption. This raises questions about how the observed kink modes would deposit their energy into the coronal plasma. Moreover, these observations, combined with the results of Monte Carlo simulations, lead us to infer that the solar corona displays a spectrum of density ratios, with a smaller density ratio (relative to the ambient corona) in quiescent coronal loops and a higher density ratio in active-region coronal loops.

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Solar feature tracking in both spatial and temporal domains

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308014981 ◽

2007 ◽

Vol 3 (S247) ◽

pp. 288-295

Author(s):

D. B. Jess ◽

M. Mathioudakis ◽

R. Erdélyi ◽

G. Verth ◽

R. T. J. McAteer ◽

...

Keyword(s):

Coronal Loop ◽

Feature Tracking ◽

New Method ◽

Kink Mode ◽

Spatial Periodicity ◽

Mode Oscillation ◽

Oscillatory Power ◽

Solar Feature

AbstractA new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. The reliability of this technique was tested with TRACE 171 Å observations. The application of this technique to a flare-induced kink-mode oscillation, revealed a 3500 km spatial periodicity which occur along the loop edge. We establish a reduction in oscillatory power, for these spatial periodicities, of 45% over a 322 s interval. We relate the reduction in oscillatory power to the physical damping of these loop-top oscillations.

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Resonant absorption of kink magnetohydrodynamic waves by a magnetic twist in coronal loops

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stw1677 ◽

2016 ◽

Vol 462 (1) ◽

pp. 1002-1011 ◽

Cited By ~ 7

Author(s):

Zanyar Ebrahimi ◽

Kayoomars Karami

Keyword(s):

Resonant Absorption ◽

Coronal Loops ◽

Magnetohydrodynamic Waves

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Decayless Kink Oscillations Excited by Random Driving: Motion in Transitional Layer

Solar Physics ◽

10.1007/s11207-021-01867-5 ◽

2021 ◽

Vol 296 (8) ◽

Author(s):

M. S. Ruderman ◽

N. S. Petrukhin ◽

E. Pelinovsky

Keyword(s):

Coronal Loop ◽

Radial Displacement ◽

Oscillation Amplitude ◽

Radial Distance ◽

Magnetic Pressure ◽

Pressure Perturbation ◽

Transitional Layer ◽

Thin Boundary Layer ◽

Plasma Displacement ◽

Thin Tube

AbstractIn this article we study the plasma motion in the transitional layer of a coronal loop randomly driven at one of its footpoints in the thin-tube and thin-boundary-layer (TTTB) approximation. We introduce the average of the square of a random function with respect to time. This average can be considered as the square of the oscillation amplitude of this quantity. Then we calculate the oscillation amplitudes of the radial and azimuthal plasma displacement as well as the perturbation of the magnetic pressure. We find that the amplitudes of the plasma radial displacement and the magnetic-pressure perturbation do not change across the transitional layer. The amplitude of the plasma radial displacement is of the same order as the driver amplitude. The amplitude of the magnetic-pressure perturbation is of the order of the driver amplitude times the ratio of the loop radius to the loop length squared. The amplitude of the plasma azimuthal displacement is of the order of the driver amplitude times $\text{Re}^{1/6}$ Re 1 / 6 , where Re is the Reynolds number. It has a peak at the position in the transitional layer where the local Alfvén frequency coincides with the fundamental frequency of the loop kink oscillation. The ratio of the amplitude near this position and far from it is of the order of $\ell$ ℓ , where $\ell$ ℓ is the ratio of thickness of the transitional layer to the loop radius. We calculate the dependence of the plasma azimuthal displacement on the radial distance in the transitional layer in a particular case where the density profile in this layer is linear.

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On the MHD stability of the $\vec m$ = 1 kink mode in solar coronal loops

Astronomy and Astrophysics ◽

10.1051/0004-6361:20000412 ◽

2001 ◽

Vol 367 (1) ◽

pp. 321-325 ◽

Cited By ~ 47

Author(s):

H. Baty

Keyword(s):

Coronal Loops ◽

Kink Mode ◽

Mhd Stability ◽

Solar Coronal

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Interior heating and outgassing of Proxima Cen b: Identification of critical parameters

10.5194/egusphere-egu21-2299 ◽

2021 ◽

Author(s):

Lena Noack ◽

Kristina Kislyakova ◽

Colin Johnstone ◽

Manuel Güdel ◽

Luca Fossati

Keyword(s):

Magnetic Field ◽

Induction Heating ◽

Initial Conditions ◽

Thermal Evolution ◽

Rotation Period ◽

Critical Parameters ◽

Stellar Spectrum ◽

Orbital Inclination ◽

The Past ◽

Tidal Heating

Since the discovery of a potentially low-mass exoplanet around our nearest neighbour star Proxima Centauri, several works have investigated the likelihood of a shielding atmosphere and therefore the potential surface habitability of Proxima Cen b. However, outgassing processes are influenced by several different (unknown) factors such as the actual planet mass, mantle and core composition, and different heating mechanisms in the interior. We aim to identify the critical parameters that influence the mantle and surface evolution of the planet over time, as well as to potentially constrain the time-dependent input of volatiles from mantle into the atmosphere. To study the coupled star-planet evolution, we analyse the heating produced in the interior of Proxima Cen b due to induction heating, which strongly varies with both depth and latitude. We calculate different rotation evolutionary tracks for Proxima Centauri and investigate the change in its rotation period and magnetic field strength. Unlike the Sun, Proxima Centauri possesses a very strong magnetic field of at least a few hundred Gauss, which was likely higher in the past.&#160; We apply an interior structure model for varying planet masses (derived from the unknown inclination of observation of the Proxima Centauri system) and iron weight fractions, i.e. different core sizes, in the range of observed Fe-Mg variations in the stellar spectrum.&#160; We use a mantle convection model to study the thermal evolution and outgassing efficiency of Proxima Cen b. For unknown planetary parameters such as initial conditions we chose randomly selected values. We take into account heating in the interior due to variable radioactive heat sources and latitute- and radius-dependent induction heating, and compare the heating efficiency to tidal heating. Our results show that induction heating may have been significant in the past, leading to local temperature increases of several hundreds of Kelvin (see Fig. 1). This early heating leads to an earlier depletion of the interior and volatile outgassing compared to if the planet would not have been subject to induction heating. We show that induction heating has an impact comparable to tidal heating when assuming latest estimates on its eccentricity. We furthermore find that the planet mass (linked to the planetary orbital inclination) has a first-order influence on the efficiency of outgassing from the interior.&#160;<img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.53bcd48f2cff56572630161/sdaolpUECMynit/12UGE&app=m&a=0&c=314fe555893c77417d52bf9a6bd3825f&ct=x&pn=gnp.elif&d=1" alt="" width="307" height="339">&#160;Fig 1: Local induction heating and resulting temperature variations compared to a simulation without induction heating after 1 Gyr of thermal evolution for an example rocky planet of 1.8 Earth masses with an iron content of 20 wt-%.

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3-D numerical simulations of coronal loops oscillations

Annales Geophysicae ◽

10.5194/angeo-27-3899-2009 ◽

2009 ◽

Vol 27 (10) ◽

pp. 3899-3908 ◽

Cited By ~ 16

Author(s):

M. Selwa ◽

L. Ofman

Keyword(s):

Active Regions ◽

External Source ◽

Coronal Loops ◽

Velocity Perturbation ◽

Impulsive Excitation ◽

Kink Mode ◽

Parametric Studies ◽

Field Lines ◽

Significant Distance

Abstract. We present numerical results of 3-D MHD model of a dipole active region field containing a loop with a higher density than its surroundings. We study different ways of excitation of vertical kink oscillations by velocity perturbation: as an initial condition, and as an impulsive excitation with a pulse of a given position, duration, and amplitude. These properties are varied in the parametric studies. We find that the amplitude of vertical kink oscillations is significantly amplified in comparison to horizontal kink oscillations for exciters located centrally (symmetrically) below the loop, but not if the exciter is located a significant distance to the side of the loop. This explains why the pure vertical kink mode is so rarely observed in comparison to the horizontally polarized one. We discuss the role of curved magnetic field lines and the pulse overlapping at one of the loop's footpoints in 3-D active regions (AR's) on the excitation and the damping of slow standing waves. We find that footpoint excitation becomes more efficient in 3-D curved loops than in 2-D curved arcades and that slow waves can be excited within an interval of time that is comparable to the observed one wave-period due to the combined effect of the pulse inside and outside the loop. Additionally, we study the effect of AR topology on the excitation and trapping of loop oscillations. We find that a perturbation acting directly on a single loop excites oscillations, but results in an increased leakage compared to excitation of oscillations in an AR field by an external source.

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