Vertical oscillations of a coronal loop observed by TRACE

Wang, Tongjiang; Solanki, S. K.

doi:10.1051/0004-6361:20040186

Cited by 156 publications

(215 citation statements)

References 13 publications

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“…This matches both the observational data (compare with Fig. 3 in Wang & Solanki 2004) and impulsively excited oscillations (compare with Fig. 2 in Selwa et al 2005).…”

Section: Resultssupporting

confidence: 90%

“…The identified wave modes include both slow propagating (De Moortel et al 2002) and slow standing 2003a,b;Ofman & Wang 2002) waves, sausage waves (Nakariakov et al 2003;Aschwanden et al 2004), and two polarizations of kink oscillations called horizontal (Aschwanden et al 1999;Nakariakov et al 1999;Schrijver et al 2002) and vertical (Wang & Solanki 2004). Although these two polarizations are similar in nature, they differ in some properties (e.g., signs of compressibility are displayed by the vertical kink oscillations only).…”

Section: Introductionmentioning

confidence: 99%

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Excitation of vertical kink waves in a solar coronal arcade loop by a periodic driver

Selwa

Murawski

Solanki

et al. 2010

A&A

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Aims. We study an oscillatory driver as a possible excitation mechanism of vertical kink loop oscillations in the ideal MHD regime. Methods. We consider a solar coronal magnetic arcade with a dense photospheric layer. The two-dimensional numerical model that we implement includes the effects of nonlinearity and line curvature on the excitation and attenuation of fast magnetosonic kink waves. We investigate the effects of a driven sinusoidal pressure pulse and compare it with the impulsive excitation by a pressure pulse that impacts the overlying loop. Results. Our numerical simulations reveal wave signatures that are reminiscent of vertical loop oscillations seen in TRACE observational data. Conclusions. We conclude that attenuation of vertical kink oscillations can be reduced to the value observed by adopting an oscillatory instead of an impulsive excitation. An oscillatory driver also naturally explains why only a small subset of all loops is excited to oscillate transversally in an active region.

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“…This matches both the observational data (compare with Fig. 3 in Wang & Solanki 2004) and impulsively excited oscillations (compare with Fig. 2 in Selwa et al 2005).…”

Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Excitation of vertical kink waves in a solar coronal arcade loop by a periodic driver

Selwa

Murawski

Solanki

et al. 2010

A&A

Self Cite

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show abstract

“…There are significant differences in the periods and displacement amplitudes for oscillations that are either observed with TRACE at temperatures of ≈1 MK or with SUMER in hot iron lines with formation temperatures of more than 6 MK. Vertical oscillations of coronal loops could also be observed by TRACE in its 19.5 nm channel (Wang and Solanki 2004).…”

Section: Coronal Oscillations and Wavesmentioning

confidence: 85%

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

et al. 2007

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In Part I of this review, the concepts of solar vacuum-ultraviolet (VUV) observations were outlined together with a discussion of the space instrumentation used for the investigations. A section on spectroradiometry provided some quantitative results on the solar VUV radiation without considering any details of the solar phenomena leading to the radiation. Here, in Part II, we present solar VUV observations over the last decades and their interpretations in terms of the plasma processes and the parameters of the solar atmosphere, with emphasis on the spatial and thermal structures of the chromosphere, transition region and corona of the quiet Sun. In addition, observations of active regions, solar flares and prominences are included as well as of small-scale events. Special sections are devoted to the elemental composition of the solar atmosphere and theoretical considerations on the heating of the corona and the generation of the solar wind.

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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: 91%

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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Vertical oscillations of a coronal loop observed by TRACE

Cited by 156 publications

References 13 publications

Excitation of vertical kink waves in a solar coronal arcade loop by a periodic driver

Excitation of vertical kink waves in a solar coronal arcade loop by a periodic driver

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

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

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