Doppler Shift Oscillations of Hot Solar Coronal Plasma Seen by SUMER: A Signature of Loop Oscillations?

Wang, Tongjiang; Solanki, S. K.; Curdt, W.; Innes, D. E.; Dammasch, I. E.

doi:10.1086/342189

Cited by 228 publications

(179 citation statements)

References 19 publications

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“…Standing waves in hot (T 6 MK) coronal loops were observed by the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer onboard the SOHO spacecraft (Kliem et al 2002;Wang et al 2002Wang et al , 2003a. Observations of 17 events revealed that the oscillation periods ranged from 11 to 31 min, and the decay time from 5.5 to 29 min.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear damped standing slow waves in hot coronal magnetic loops

Ruderman

2013

A&A

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We study the nonlinear standing slow waves in coronal magnetic loops. We assume that the wave amplitude is sufficiently small and use it as a small parameter in the asymptotic expansions. In addition, we assume that the wave damping is sufficiently slow, which enables us to introduce the "slow" time related to the evolution of the wave amplitude and shape. We show that, in the leading-order approximation, the nonlinear standing wave is a superposition of two identical nonlinear waves propagating in the opposite directions. The two waves are governed by the Burgers equation. Using the Cole-Hopfe substitution, we obtain an analytical solution describing a standing wave that has the form of the linear fundamental eigenmode at the initial moment of time. This solution is used for the parametric study of nonlinear standing waves. In particular, the effect of nonlinearity on the oscillation damping time is investigated.

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Section: Introductionmentioning

confidence: 99%

Nonlinear damped standing slow waves in hot coronal magnetic loops

Ruderman

2013

A&A

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“…Several different types of MHD wave motions have now been observed by various solar instruments: slow magnetoacoustic waves have been seen in SOHO data (e.g. 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).…”

Section: Introductionmentioning

confidence: 99%

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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“…A&A 578, A60 (2015) In this paper we focus on axisymmetric slow and fast sausage modes, which have recently been discovered in numerous structures, but have not been adequately modelled to estimate their energy content. They have been detected in coronal loops (De Moortel et al 2000;Wang et al 2002Wang et al , 2003Krishna Prasad et al 2012), in photospheric pores (Dorotovič et al 2008(Dorotovič et al , 2014Morton et al 2011;Moreels et al 2015), in network bright points (McAteer et al 2003;Bharti et al 2006;Martínez González et al 2011), in flares (Nakariakov et al 2003;Melnikov et al 2005;Van Doorsselaere et al 2011), and in the chromosphere (Morton et al 2012a). Some authors have attempted to estimate the amount of energy present in these observations.…”

Section: Introductionmentioning

confidence: 99%

Energy and energy flux in axisymmetric slow and fast waves

Moreels

Doorsselaere

Grant

et al. 2015

A&A

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Aims. We aim to calculate the kinetic, magnetic, thermal, and total energy densities and the flux of energy in axisymmetric sausage modes. The resulting equations should contain as few parameters as possible to facilitate applicability for different observations. Methods. The background equilibrium is a one-dimensional cylindrical flux tube model with a piecewise constant radial density profile. This enables us to use linearised magnetohydrodynamic equations to calculate the energy densities and the flux of energy for axisymmetric sausage modes.Results. The equations used to calculate the energy densities and the flux of energy in axisymmetric sausage modes depend on the radius of the flux tube, the equilibrium sound and Alfvén speeds, the density of the plasma, the period and phase speed of the wave, and the radial or longitudinal components of the Lagrangian displacement at the flux tube boundary. Approximate relations for limiting cases of propagating slow and fast sausage modes are also obtained. We also obtained the dispersive first-order correction term to the phase speed for both the fundamental slow body mode under coronal conditions and the slow surface mode under photospheric conditions.

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Doppler Shift Oscillations of Hot Solar Coronal Plasma Seen by SUMER: A Signature of Loop Oscillations?

Cited by 228 publications

References 19 publications

Nonlinear damped standing slow waves in hot coronal magnetic loops

Nonlinear damped standing slow waves in hot coronal magnetic loops

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

Energy and energy flux in axisymmetric slow and fast waves

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