TRACE Observation of Damped Coronal Loop Oscillations: Implications for Coronal Heating

Nakariakov, V. M.; Ofman, L.; DeLuca, E. E.; Roberts, B.; Davila, J. M.

doi:10.1126/science.285.5429.862

Cited by 869 publications

(818 citation statements)

References 20 publications

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“…Ofman et al 1997;DeForest & Gurman 1998;Berghmans & Clette 1999;Kliem et al 2002;Wang et al 2002) and TRACE data (De Moortel et al 2000). Fast magnetoacoustic waves have been seen with TRACE (Aschwanden et al 1999(Aschwanden et al , 2002Nakariakov et al 1999;Wang & Solanki 2004) and Hinode (Ofman & Wang 2008). Non-thermal line narrowing / broadening due to Alfvén waves has been reported by Harrison et al (2002) / Erdélyi et al (1998), Banerjee et al (1998) and O'Shea et al (2003).…”

Section: Introductionmentioning

confidence: 67%

Review Article: MHD Wave Propagation Near Coronal Null Points of Magnetic Fields

McLaughlin¹,

Hood²,

Moortel³

2010

Space Sci Rev

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We present a comprehensive review of MHD wave behaviour in the neighbourhood of coronal null points: locations where the magnetic field, and hence the local Alfvén speed, is zero. The behaviour of all three MHD wave modes, i.e. the Alfvén wave and the fast and slow magnetoacoustic waves, has been investigated in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null points, for a variety of assumptions, configurations and geometries. In general, it is found that the fast magnetoacoustic wave behaviour is dictated by the Alfvén-speed profile. In a β = 0 plasma, the fast wave is focused towards the null point by a refraction effect and all the wave energy, and thus current density, accumulates close to the null point. Thus, null points will be locations for preferential heating by fast waves. Independently, the Alfvén wave is found to propagate along magnetic fieldlines and is confined to the fieldlines it is generated on. As the wave approaches the null point, it spreads out due to the diverging fieldlines. Eventually, the Alfvén wave accumulates along the separatrices (in 2D) or along the spine or fan-plane (in 3D). Hence, Alfvén wave energy will be preferentially dissipated at these locations. It is clear that the magnetic field plays a fundamental role in the propagation and properties of MHD waves in the neighbourhood of coronal null points. This topic is a fundamental plasma process and results so far have also lead to critical insights into reconnection, mode-coupling, quasi-periodic pulsations and phase-mixing.

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Section: Introductionmentioning

confidence: 67%

Review Article: MHD Wave Propagation Near Coronal Null Points of Magnetic Fields

McLaughlin¹,

Hood²,

Moortel³

2010

Space Sci Rev

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“…They have been detected with confidence ever since 1998 (Aschwanden et al 1999;Nakariakov et al 1999) in the form of transverse loop oscillations (TLOs). To date, more than 50 TLOs have been reported with periods ranging between 100 s and 3 h Wang & Solanki 2004;Verwichte et al 2004;Hori et al 2005Hori et al , 2007Van Doorsselaere et al 2007De Moortel & Brady 2007;Verwichte et al 2009Verwichte et al , 2010Mrozek 2011;Verwichte et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Statistical seismology of transverse waves in the solar corona

Verwichte

Doorsselaere

White

et al. 2013

A&A

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Context. Observations show that transverse oscillations commonly occur in solar coronal loops. The rapid damping of these waves has been attributed to resonant absorption. The oscillation characteristics carries information of the structuring of the corona. However, self-consistent seismological methods that extract information from individual oscillations are limited because there are fewer observables than unknown parameters in the model, and the problem is underdetermined. Furthermore, it has been shown that one-to-one comparisons of the observed scaling of period and damping times with wave damping theories are misleading. Aims. We aim to investigate whether seismological information can be gained from the observed scaling laws in a statistical sense. Methods. A statistical approach is used whereby scaling laws are produced by forward modelling using distributions of values for key loop cross-sectional structuring parameters. We study two types of observations: 1) transverse loops oscillations as seen mainly with TRACE and SDO and 2) running transverse waves seen with the Coronal Multichannel Polarimeter (CoMP). Results. We demonstrate that the observed period-damping time scaling law does provide information about the physical damping mechanism, if observations are collected from as wide range of periods as possible and a comparison with theory is performed in a statistical sense. The distribution of the ratio of damping time over period, i.e. the quality factor, has been derived analytically and fitted to the observations. A minimum value for the quality factor of 0.65 has been found. From this, a constraint linking the ranges of possible values for the density contrast and inhomogeneity layer thickness is obtained for transverse loop oscillations. If the layer thickness is not constrained, then the density contrast is at most equal to 3. For transverse waves seen by CoMP, it is found that the ratio of maximum to minimum values for these two parameters has to be less than 2.06; i.e., the sampled values for the layer thickness and Alfvén travel time come from a relatively narrow distribution. Conclusions. Now that more and more transverse loop oscillations have been analysed, a statistical approach to coronal seismology becomes possible. Using the observed data cloud, we have found restrictions to the loop's density contrast and inhomogeneity layer thickness. Surprisingly, for running waves, narrow distributions for loop parameters have been found.

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“…After transverse oscillations of coronal magnetic loops were first observed by the Transition Region and Coronal Explorer (TRACE) spacecraft and reported by Aschwanden et al (1999) and Nakariakov et al (1999), they received ample attention from solar physicists. These oscillations have been interpreted as fast standing kink body waves in cylindrical magnetic flux tubes.…”

Section: Introductionmentioning

confidence: 99%

Kink oscillations of cooling coronal loops with variable cross-section

Shukhobodskiy

Erdélyi

2017

A&A

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We study kink waves and oscillations in a thin expanding magnetic tube in the presence of flow. The tube consists of a core region and a thin transitional region at the tube boundary. In this region the plasma density monotonically decreases from its value in the core region to the value outside the tube. Both the plasma density and velocity of background flow vary along the tube and in time. Using the multiscale expansions we derive the system of two equations describing the kink oscillations. When there is no transitional layer the oscillations are described by the first of these two equations. We use this equation to study the effect of plasma density variation with time on kink oscillations of an expanding tube with a sharp boundary. We assume that the characteristic time of the density variation is much greater than the characteristic time of kink oscillations. Then we use the Wentzel-Kramer-Brillouin (WKB) method to derive the expression for the adiabatic invariant, which is the quantity that is conserved when the plasma density varies. The general theoretical results are applied to the kink oscillations of coronal magnetic loops. We consider an expanding loop with the half-circle shape and assume that the plasma temperature inside a loop decays exponentially with time. We numerically calculated the dependences of the fundamental mode frequency, the ratio of frequencies of the first overtone and fundamental mode, and the oscillation amplitude on time. We obtained that the oscillation frequency and amplitude increase and the frequency ratio decreases due to cooling. The amplitude increase is stronger for loops with a greater expansion factor. This effect is also more pronounced for higher loops. However, it is fairly moderate even for loops that are quite high.

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TRACE Observation of Damped Coronal Loop Oscillations: Implications for Coronal Heating

Cited by 869 publications

References 20 publications

Review Article: MHD Wave Propagation Near Coronal Null Points of Magnetic Fields

Review Article: MHD Wave Propagation Near Coronal Null Points of Magnetic Fields

Statistical seismology of transverse waves in the solar corona

Kink oscillations of cooling coronal loops with variable cross-section

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