The effect of density stratification on the transverse oscillations of two parallel coronal loops

Robertson, Daniel; Taroyan, Y.

doi:10.1051/0004-6361/201014055

Cited by 16 publications

(9 citation statements)

References 20 publications

(38 reference statements)

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“…Ruderman (2007) has shown that the twist of magnetic field lines in the loop can be safely neglected when estimating the atmospheric scale height in the corona. Robertson et al (2010) found that the estimates of the atmospheric scale height obtained using the two-thread model are exactly the same as those obtained using the model of a monolithic coronal loop with a circular cross-section of constant radius. Recently Ruderman (2010) showed that the account of stationary time independent siphon flows in coronal loops have little influence on the estimates of the coronal scale height found using the frequency ratio.…”

Section: Implication On Coronal Seismologysupporting

confidence: 59%

Kink and fluting modes of stratified coronal magnetic loops with elliptical cross-sections

Morton¹

2011

A&A

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Aims. We study kink and fluting oscillations of a straight magnetic tube with an elliptic cross-section and density varying along the tube. Methods. The governing equations for kink and fluting modes in the thin tube approximation are derived. We found that there are two kink modes, polarised along the semimajor and semiminor axes of the elliptic cross-section. We have shown that the ratio of frequencies of the first overtone and fundamental mode is the same for both kink modes and independent of the ratio of the ellipse axes.Results. On the basis of this result we concluded that the estimates of the atmospheric scale height obtained using simultaneous observations of the fundamental mode and first overtone of the coronal loop kink oscillations are independent of the ellipticity of the loop cross-section.

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Section: Implication On Coronal Seismologysupporting

confidence: 59%

Kink and fluting modes of stratified coronal magnetic loops with elliptical cross-sections

Morton¹

2011

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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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“…Luna et al (2009Luna et al ( , 2010 studied oscillations of multi-stranded coronal loops and systems A&A 525, A4 (2011) of many interacting coronal loops using the T -matrix theory. Robertson et al (2010) investigated the effect of density variation along the loop in the two-loop system. The problem of damping of kink oscillations of multi-loop systems has been also addressed.…”

Section: Introductionmentioning

confidence: 99%

Resonantly damped oscillations of two coronal loops

Robertson

2010

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Transverse oscillations of coronal magnetic loops are routinely observed during the space missions. Since the first observation these oscillations were interpreted in terms of kink oscillations of magnetic tubes. Sometimes collective oscillations of two or more coronal loops are observed. This makes the development of theory of collective oscillations of a few parallel magnetic tubes desirable. Another reason for the development of this theory is that there are evidences that at least some coronal loops are not monolithic but consist of many thin magnetic threads. In this paper the linear theory of resonant damping of kink oscillations of two parallel magnetic tubes is developed. Two small parameters, the ratio of the distance between the tubes to the tube length and the ratio of thickness of regions with varying density to the tube radius, are used to obtain the asymptotic expression for the decrement. This expression is calculated explicitly in a particular case of two identical tubes. The dependence of damping time on the separation distance between the tubes and on the density contrast is investigated. In particular, we obtained that the interaction between the tubes reduces the efficiency of resonant absorption.

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The effect of density stratification on the transverse oscillations of two parallel coronal loops

Cited by 16 publications

References 20 publications

Kink and fluting modes of stratified coronal magnetic loops with elliptical cross-sections

Kink and fluting modes of stratified coronal magnetic loops with elliptical cross-sections

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

Resonantly damped oscillations of two coronal loops

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