Kelvin–Helmholtz instability in a twisting solar polar coronal hole jet observed by SDO/AIA

Zhelyazkov, I.; Zaqarashvili, T. V.; Ofman, L.; Chandra, Ramesh

doi:10.1016/j.asr.2017.06.003

Cited by 15 publications

(15 citation statements)

References 54 publications

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“…During its evolution in 304 Å we found the blob structures at the jet boundary. These blobs could be due to the KHI as reported in previous observations (see, for example Zhelyazkov et al, 2018a). At the jet initiation/base site, we observed the coronal hole bright points.…”

Section: Kelvin-helmholtz Instability In a Blowout Polar Coronal Holesupporting

confidence: 86%

“…In this article, we also corrected the total pressure balance equation used in Zhelyazkov et al, 2018a andChandra, 2018b, which turns out to be erroneous. The true total balance equation is given by equation (3).…”

Section: Discussionmentioning

confidence: 99%

“…As observations show, the KHI vortex-like structures running at the boundary of the jet, have the size of the width or radius of the flux tube (see, for instance, Fig. 1 in Zhelyazkov et al, 2018a). Therefore, we have to look for such an m, whose instability range would accommodate the expected unstable wavelength presented by its nondimensional wavenumber, k z a = π∆ℓ/λ KH .…”

Section: Numerical Solutions Wave Dispersion and Growth Rate Diagramsmentioning

confidence: 99%

See 2 more Smart Citations

How Rotating Solar Atmospheric Jets Become Kelvin–Helmholtz Unstable

Zhelyazkov

Chandra

Joshi

2019

Front. Astron. Space Sci.

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Recent observations support the propagation of a number of magnetohydrodynamic (MHD) modes which, under some conditions, can become unstable and the developing instability is the Kelvin-Helmholtz instability (KHI). In its nonlinear stage the KHI can trigger the occurrence of wave turbulence which is considered as a candidate mechanism for coronal heating. We review the modeling of tornado-like phenomena in the solar chromosphere and corona as moving weakly twisted and spinning cylindrical flux tubes, showing that the KHI rises at the excitation of high-mode MHD waves. The instability occurs within a wavenumber range whose width depends on the MHD mode number m, the plasma density contrast between the rotating jet and its environment, and also on the twists of the internal magnetic field and the jet velocity. We have studied KHI in two twisted spinning solar polar coronal hole jets, in a twisted rotating jet emerging from a filament eruption, and in a rotating macrospicule. The theoretically calculated KHI development times of a few minutes for wavelengths comparable to the half-widths of the jets are in good agreement with the observationally determined growth times only for high order (10 m 65) MHD modes. Therefore, we expect that the observed KHI in these cases is due to unstable high-order MHD modes.

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Section: Kelvin-helmholtz Instability In a Blowout Polar Coronal Holesupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Section: Numerical Solutions Wave Dispersion and Growth Rate Diagramsmentioning

confidence: 99%

See 1 more Smart Citation

How Rotating Solar Atmospheric Jets Become Kelvin–Helmholtz Unstable

Zhelyazkov

Chandra

Joshi

2019

Front. Astron. Space Sci.

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“…They can be found on the interface between an erupting/dimming region and the surrounding corona in AIA EUV passbands (Ofman & Thompson 2011). The vortex-like structures of KHIs were also detected on the boundary of a filament which embedded in a CME (Möstl et al 2013) or along the boundary of a twisting solar polar coronal hole jet (Shen et al 2011b;Zhelyazkov et al 2018) at lower temper-ature, such as AIA 304Å. Beside the SDO/AIA observations, Feng et al (2013) reported a KHI in a coronal streamer which detected by the Solar and Heliospheric Observatory (SOHO).…”

Section: Introductionmentioning

confidence: 99%

Two Kinds of Dynamic Behavior in a Quiescent Prominence Observed by the NVST

Shen

Ning

et al. 2018

ApJ

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We present high-resolution observations of two kinds of dynamic behavior in a quiescent prominence using the New Vacuum Solar Telescope, i.e., Kelvin-Helmholtz instabilities (KHIs) and small-scale oscillations. The KHIs were identified as rapidly developed vortex-like structures with counter-clockwise/clockwise rotations in the Hα red-wing images at +0.3Å, which were produced by the strong shear-flows motions on the surface/interface of prominence plumes. The KHI growth rates are estimated to be ∼0.0135±0.0004 and ∼0.0138±0.0004. Our observational results further suggest that the shear velocities (i.e, supersonic) of the mass flows are fast enough to produce the strong deformation of the boundary and overcome the restraining surface tension force. This flow-driven instability might play a significant role in the process of plasma transfer in solar prominences. The small-scale oscillations perpendicular to the prominence threads are observed in the Hα line-center images. The oscillatory periods changed non-monotonically and showed two changing patterns, in which one firstly decreased slowly and then it changed to increase, while the other grew fast at the beginning and then it changed to decrease. Both of these two thread oscillations with changing periods were observed to be unstable for an entire cycle, and they were local in nature. All our findings indicate that the small-scale thread oscillations could be magnetohydrodynamic waves in the solar corona.

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“…Rossby waves and their coupling with solar activity are analysed (Zaqarashvili and Gurgenashvili 2018). Solar magnetic tubes, their effect on solar wind turbulence and its heating is studied (Zhelyazkov et al 2018). Outer corona dynamics in radio waves are also analyzed (Pylaev et al 2017).…”

Section: Research Topicsmentioning

confidence: 99%

Astronomical Research and Outreach in Georgia

Todua¹

2018

ComBAO

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Interest in astronomy has been significantly increased in Georgia. As a result, the development of astronomical research, education and public outreach are in progress. In Abastumani Astrophysical Observatory - a research institution at Ilia State University - the observational and theoretical studies comprise a wide range of topics in astronomy and adjacent fields: solar system bodies, solar physics, stellar and extragalactic astronomy, theoretical astrophysics, cosmology, atmospheric and near space physics. Georgian scientists are involved in wide international collaboration and participate in a number of networks and projects. Astronomical education at bachelor, master and doctoral levels are held at Ilia University. PhD programs are also offered at other universities. In 2018, under the financial support of the World Bank and Georgian government, the renovation of Abastumani Observatory has been started. International conferences and workshops have been carried out in Georgia. Excursions at the Observatory and public lectures in astronomy throughout the country are carried out. Amateur astronomers organize astronomical events. A private observatory is under construction near Tbilisi. All these puts better perspective for future development of astronomy in Georgia.

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Kelvin–Helmholtz instability in a twisting solar polar coronal hole jet observed by SDO/AIA

Cited by 15 publications

References 54 publications

How Rotating Solar Atmospheric Jets Become Kelvin–Helmholtz Unstable

How Rotating Solar Atmospheric Jets Become Kelvin–Helmholtz Unstable

Two Kinds of Dynamic Behavior in a Quiescent Prominence Observed by the NVST

Astronomical Research and Outreach in Georgia

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