The excitation of 5-min oscillations in the solar corona

Zaqarashvili, T. V.; Murawski, K.; Khodachenko, M. L.; Lee, D.

doi:10.1051/0004-6361/201015384

Cited by 12 publications

(12 citation statements)

References 28 publications

(35 reference statements)

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“…This mechanism has been identified in many observational and theoretical studies (e.g. De Moortel, Ireland, and Walsh, 2000;Marsh et al, 2003;De Pontieu, Erdélyi, and James, 2004;De Pontieu, Erdélyi, and De Moortel, 2005;Didkovsky et al, 2011;Zaqarashvili et al, 2011). Hence we can propose that the leakage of oscillation modes from the layers below the corona is also an important driving mechanism for the generation of the observed QFP wave in the low corona, in line with our previous results (Shen and Liu, 2012a).…”

Section: The Generation Of the Qfp Wavesupporting

confidence: 91%

Observations of a Quasi-periodic, Fast-Propagating Magnetosonic Wave in Multiple Wavelengths and Its Interaction with Other Magnetic Structures

Shen

Liu

et al. 2013

Sol Phys

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We present observations of a quasi-periodic fast-propagating (QFP) magnetosonic wave on 23 April 2012, with high-resolution observations taken by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. Three minutes after the start of a C2.0 flare, wave trains were first observed along an open divergent loop system in 171Å observations at a distance of 150 Mm from the footpoint of the guiding loop system and with a speed of 689 km s −1 , then they appeared in 193Å observations after their interaction with a perpendicular, underlaying loop system on the path; in the meantime; their speed decelerated to 343 km s −1 within a short time. The sudden deceleration of the wave trains and their appearance in 193Å observations are interpreted through a geometric effect and the density increase of the guiding loop system, respectively. We find that the wave trains have a common period of 80 seconds with the flare. In addition, a few low frequencies are also identified in the QFP wave. We propose that the generation of the period of 80 seconds was caused by the periodic releasing of energy bursts through some nonlinear processes in magnetic reconnection, while the low frequencies were possibly the leakage of pressure-driven oscillations from the photosphere or chromosphere, which could be an important source for driving coronal QFP waves. Our results also indicate that the properties of the guiding magnetic structure, such as the distributions of magnetic field and density as well as geometry, are crucial for modulating the propagation behaviors of QFP waves.

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Section: The Generation Of the Qfp Wavesupporting

confidence: 91%

Observations of a Quasi-periodic, Fast-Propagating Magnetosonic Wave in Multiple Wavelengths and Its Interaction with Other Magnetic Structures

Shen

Liu

et al. 2013

Sol Phys

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“…However, Murawski and Zaqarashvili (2010) and Zaqarashvili et al (2011) suggested that the observed periodicity in the solar corona is caused by quasi-periodic rebound shocks, originating from nonlinear wakes in the stratified atmosphere. Here we have developed the same idea and solved the ideal MHD equations in the case of a realistic temperature profile.…”

Section: Discussionmentioning

confidence: 99%

Numerical simulations of magnetoacoustic oscillations in a gravitationally stratified solar corona

Konkol

Murawski

Zaqarashvili

2012

A&A

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Aims. We consider magnetoacoustic oscillations in a gravitationally stratified solar corona, that are triggered by an initial pulse in the vertical component of velocity launched from various altitudes of the solar atmosphere. Methods. We numerically solve two-dimensional magnetohydrodynamic equations for an ideal plasma to determine the spatial and temporal signatures of excited oscillations. Results. Our numerical results reveal that few-min oscillations are effectively excited by the initial velocity pulses and that their waveperiods depend on the vertical location and amplitude of the pulse. Conclusions. The building block of this scenario consists of a one-dimensional rebound shock model.

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“…The amplitude of oscillations is stronger at greater height, but oscillations decay rapidly at each height as time progresses. and acoustic oscillations (Murawski & Zaqarashvili 2010;Zaqarashvili et al 2011) near the acoustic cut-off period of the chromosphere. In a similar way, the recurrent shocks may cause the density oscillations in the higher corona with the coronal acoustic cut-off period, which is much greater than that of the chromosphere.…”

Section: Oscillation Of Coronal Plasma At Acoustic Cut-off Frequency mentioning

confidence: 99%

Oscillation of solar radio emission at coronal acoustic cut-off frequency

Pylaev

Zaqarashvili

Браженко

et al. 2017

A&A

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Recent SECCHI COR2 observations on board STEREO-A spacecraft have detected density structures at a distance of 2.5-15 R 0 propagating with periodicity of about 90 minutes. The observations show that the density structures probably formed in the lower corona. We used the large Ukrainian radio telescope URAN-2 to observe type IV radio bursts in the frequency range of 8-32 MHz during the time interval of 08:15-11:00 UT on August 1, 2011. Radio emission in this frequency range originated at the distance of 1.5-2.5 R 0 according to the Baumbach-Allen density model of the solar corona. Morlet wavelet analysis showed the periodicity of ∼80 min in radio emission intensity at all frequencies, which demonstrates that there are quasi-periodic variations of coronal density at all heights. The observed periodicity corresponds to the acoustic cut-off frequency of stratified corona at a temperature of 1 MK. We suggest that continuous perturbations of the coronal base in the form of jets/explosive events generate acoustic pulses, which propagate upwards and leave the wake behind oscillating at the coronal cut-off frequency. This wake may transform into recurrent shocks due to the density decrease with height, which leads to the observed periodicity in the radio emission. The recurrent shocks may trigger quasi-periodic magnetic reconnection in helmet streamers, where the opposite field lines merge and consequently may generate periodic density structures observed in the solar wind.

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The excitation of 5-min oscillations in the solar corona

Cited by 12 publications

References 28 publications

Observations of a Quasi-periodic, Fast-Propagating Magnetosonic Wave in Multiple Wavelengths and Its Interaction with Other Magnetic Structures

Observations of a Quasi-periodic, Fast-Propagating Magnetosonic Wave in Multiple Wavelengths and Its Interaction with Other Magnetic Structures

Numerical simulations of magnetoacoustic oscillations in a gravitationally stratified solar corona

Oscillation of solar radio emission at coronal acoustic cut-off frequency

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