Resonantly damped oscillations of two coronal loops

Robertson, Daniel

doi:10.1051/0004-6361/201015525

Cited by 13 publications

(36 citation statements)

References 34 publications

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“…A model for collections of flux tubes with higher filling factors would essentially need to take into account the interaction between neighboring flux tubes. An initial attempt could be made in a two-loop system, using the bicylindrical coordinates (Van Doorsselaere et al 2008c;Robertson et al 2010;Robertson & Ruderman 2011;Gijsen & Van Doorsselaere 2014). Ultimately, one would need to calculate the energy flux using the T-matrix formulation that takes into account the interaction in systems of more than two flux tubes (e.g., Bogdan & Cattaneo 1989;Keppens et al 1994;Luna et al 2009Luna et al , 2010.…”

Section: Connecting the Energy Flux To The Filling Factormentioning

confidence: 99%

Energy Propagation by Transverse Waves in Multiple Flux Tube Systems Using Filling Factors

Doorsselaere

Gijsen

Andries

et al. 2014

ApJ

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In the last few years, it has been found that transverse waves are present at all times in coronal loops or spicules. Their energy has been estimated with an expression derived for bulk Alfvén waves in homogeneous media, with correspondingly uniform wave energy density and flux. The kink mode, however, is localized in space with the energy density and flux dependent on the position in the cross-sectional plane. The more relevant quantities for the kink mode are the integrals of the energy density and flux over the cross-sectional plane. The present paper provides an approximation to the energy propagated by kink modes in an ensemble of flux tubes by means of combining the analysis of single flux tube kink oscillations with a filling factor for the tube cross-sectional area. This finally allows one to compare the expressions for energy flux of Alfvén waves with an ensemble of kink waves. We find that the correction factor for the energy in kink waves, compared to the bulk Alfvén waves, is between f and 2f , where f is the density filling factor of the ensemble of flux tubes.

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Section: Connecting the Energy Flux To The Filling Factormentioning

confidence: 99%

Energy Propagation by Transverse Waves in Multiple Flux Tube Systems Using Filling Factors

Doorsselaere

Gijsen

Andries

et al. 2014

ApJ

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“…Their results were adapted to coronal conditions by Soler (2010), who solved the resulting system of equations numerically. Recently, Robertson & Ruderman (2011) developed a fully analytic model for the damped oscillations of a system of two identical parallel coronal loops. This paper aims to generalise the results of Robertson & Ruderman (2011) to a system of two not necessarily identical parallel loops.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Robertson & Ruderman (2011) developed a fully analytic model for the damped oscillations of a system of two identical parallel coronal loops. This paper aims to generalise the results of Robertson & Ruderman (2011) to a system of two not necessarily identical parallel loops. The density contrast between the two loops is an important parameter that characterises the interaction between the loops; hence this parameter cannot be ignored.…”

Section: Introductionmentioning

confidence: 99%

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Resonantly damped oscillations of a system of two coronal loops

Gijsen

Doorsselaere

2014

A&A

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Context. Rapidly damped transverse oscillations of coronal loop systems are often observed. Aims. We aim to study analytically the resonantly damped oscillations of a system of two not necessarily identical coronal loops and their dependence on the equilibrium parameters, improving on and extending the results for two identical coronal loops. Methods. The linearised magnetohydrodynamic equations for a cold plasma were solved in the long-wavelength limit and for thin boundary layers in bicylindrical coordinates. We investigated the effects of the density contrast between the two loops, the thickness of their inhomogeneous layers, and the separation distance between them. The complex spectrum was also studied. Results. We obtained more general expressions for the linear damping rate of the transverse oscillations in a system of two coronal loops. The results can be reduced to expressions found previously for the special cases of one vanishing loop or two identical loops. The interaction between the loops results in a stronger damping of the high-frequency eigenoscillation in comparison with that of the low-frequency eigenoscillation. By decreasing the distance between loops, the efficiency of resonant damping is reduced.

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“…The linear theory of the resonant damping of kink oscillations in two parallel magnetic tubes is also developed by Robertson and Ruderman (2011). It should be noted that the observed jet shows transverse kink oscillations of two periods : 21 min (long) and 2 min (short) (Figure 14).…”

Section: Interaction Between Jet and Loopmentioning

confidence: 92%

Transverse Oscillations in a Coronal Loop Triggered by a Jet

et al. 2016

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We detect and analyse transverse oscillations in a coronal loop, lying at the south east limb of the Sun as seen from the Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO). The jet is believed to trigger transverse oscillations in the coronal loop. The jet originates from a region close to the coronal loop on 19th September 2014 at 02:01:35 UT. The length of the loop is estimated to be between 377-539 Mm. Only one complete oscillation is detected with an average period of about 32 ± 5 min. Using MHD seismologic inversion techniques, we estimate the magnetic field inside the coronal loop to be between 2.68 − 4.5 G. The velocity of the hot and cool components of the jet is estimated to be 168 km s −1 and 43 km s −1 , respectively. The energy density of the jet is found to be greater than the energy density of the oscillating coronal loop. Therefore, we conclude that the jet triggered transverse oscillations in the coronal loop. To our knowledge, this is the first coronal loop seismology study using the properties of a jet propagation to trigger oscillations.

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Resonantly damped oscillations of two coronal loops

Cited by 13 publications

References 34 publications

Energy Propagation by Transverse Waves in Multiple Flux Tube Systems Using Filling Factors

Energy Propagation by Transverse Waves in Multiple Flux Tube Systems Using Filling Factors

Resonantly damped oscillations of a system of two coronal loops

Transverse Oscillations in a Coronal Loop Triggered by a Jet

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