Solar Magnetized Tornadoes: Rotational Motion in a Tornado-Like Prominence

Su, Yang; Gömöry, P.; Veronig, Astrid; Temmer, Manuela; Wang, Tongjiang; Vanninathan, K.; Gan, Weiqun; Li, Youping

doi:10.1088/2041-8205/785/1/l2

Cited by 54 publications

(86 citation statements)

References 27 publications

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“…It is logical then to combine imaging and spectroscopic data analysis to understand the nature of these apparent motions. This was done by Orozco Suárez et al (2012), Wedemeyer et al (2013), Su et al (2014), amongst others, and their results suggest that the observed prominence foot structure is rotating. However, their analysis leaves open a few questions related to the state of the plasma that was observed.…”

Section: Introductionmentioning

confidence: 88%

“…With the Fe xi line already removed from the blend this is a good approximation for these lines, even if the assumed density is higher than might be expected for this line - Labrosse et al (2010, Table 4 and references therein) suggest that the density of O v would be around log n e ∼ 9.5 for an active region prominence, slightly lower for quiescent prominences -the density sensitivity between these two lines at these densities is negligible, and the resulting fit is sufficient for the analysis performed here. Su et al (2014) in their analysis of this event, and here we follow a similar approach to remove the red-wing line. We take a double Gaussian fit, and as with the Fe xi doublet in Sect.…”

Section: Eis Spectral Linesmentioning

confidence: 99%

“…In this paper, we investigate the plasma properties of a solar tornado using data obtained by Hinode/EIS and SDO/AIA on 14 September 2013 (also studied by Su et al 2014). Section 2 gives an overview of the observations and explains the procedure followed for the data analysis.…”

Section: Introductionmentioning

confidence: 99%

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A solar tornado observed by EIS

Levens

Labrosse

Fletcher

et al. 2015

A&A

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Context. The term "solar tornadoes" has been used to describe apparently rotating magnetic structures above the solar limb, as seen in high resolution images and movies from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO). These often form part of the larger magnetic structure of a prominence, however the links between them remain unclear. Here we present plasma diagnostics on a tornado-like structure and its surroundings, seen above the limb by the Extreme-ultraviolet Imaging Spectrometer (EIS) aboard the Hinode satellite. Aims. We aim to extend our view of the velocity patterns seen in tornado-like structures with EIS to a wider range of temperatures and to use density diagnostics, non-thermal line widths, and differential emission measures to provide insight into the physical characteristics of the plasma. Methods. Using Gaussian fitting to fit and de-blend the spectral lines seen by EIS, we calculated line-of-sight velocities and nonthermal line widths. Along with information from the CHIANTI database, we used line intensity ratios to calculate electron densities at each pixel. Using a regularised inversion code we also calculated the differential emission measure (DEM) at different locations in the prominence. Results. The split Doppler-shift pattern is found to be visible down to a temperature of around log T = 6.0. At temperatures lower than this, the pattern is unclear in this data set. We obtain an electron density of log n e = 8.5 when looking towards the centre of the tornado structure at a plasma temperature of log T = 6.2, as compared to the surroundings of the tornado structure where we find log n e to be nearer 9. Non-thermal line widths show broader profiles at the tornado location when compared to the surrounding corona. We discuss the differential emission measure in both the tornado and the prominence body, which suggests that there is more contribution in the tornado at temperatures below log T = 6.0 than in the prominence.

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Section: Introductionmentioning

confidence: 88%

Section: Eis Spectral Linesmentioning

confidence: 99%

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A solar tornado observed by EIS

Levens

Labrosse

Fletcher

et al. 2015

A&A

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“…Orozco Suárez et al (2012) found opposite Doppler shifts at the edge of a prominence foot and interpreted these shifts as prominence plasma that rotates around the axis. Recently, Wedemeyer et al (2013) and Su et al (2014) separately found redshifted and blueshifted regions on A&A 570, A93 (2014) the two sides of the prominence leg and proposed that there is rotational motion in a tornado-like prominence. All these observations together show that spinning and twisting motions are common on the Sun.…”

Section: Introductionmentioning

confidence: 99%

Conversion from mutual helicity to self-helicity observed with IRIS

Peter

Chen

et al. 2014

A&A

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Context. In the upper atmosphere of the Sun observations show convincing evidence for crossing and twisted structures, which are interpreted as mutual helicity and self-helicity. Aims. We use observations with the new Interface Region Imaging Spectrograph (IRIS) to show the conversion of mutual helicity into self-helicity in coronal structures on the Sun. Methods. Using far UV spectra and slit-jaw images from IRIS and coronal images and magnetograms from SDO, we investigated the evolution of two crossing loops in an active region, in particular, the properties of the Si IV line profile in cool loops. Results. In the early stage two cool loops cross each other and accordingly have mutual helicity. The Doppler shifts in the loops indicate that they wind around each other. As a consequence, near the crossing point of the loops (interchange) reconnection sets in, which heats the plasma. This is consistent with the observed increase of the line width and of the appearance of the loops at higher temperatures. After this interaction, the two new loops run in parallel, and in one of them shows a clear spectral tilt of the Si IV line profile. This is indicative of a helical (twisting) motion, which is the same as to say that the loop has self-helicity. Conclusions. The high spatial and spectral resolution of IRIS allowed us to see the conversion of mutual helicity to self-helicity in the (interchange) reconnection of two loops. This is observational evidence for earlier theoretical speculations.

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“…; Wedemeyer et al 2013;Su et al 2014) have revealed vortex-type motions in different layers of the solar atmosphere and at various temporal and spatial scales. Bonet & Marquez (2008) observed magnetic bright points (MBPs) spiraling into convective downdrafts.…”

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confidence: 99%

Generation of Magnetohydrodynamic Waves in Low Solar Atmospheric Flux Tubes by Photospheric Motions

Mumford

Fedun

Erdélyi

2015

ApJ

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Recent ground-and space-based observations reveal the presence of small-scale motions between convection cells in the solar photosphere. In these regions, small-scale magnetic flux tubes are generated via the interaction of granulation motion and the background magnetic field. This paper studies the effects of these motions on magnetohydrodynamic (MHD) wave excitation from broadband photospheric drivers. Numerical experiments of linear MHD wave propagation in a magnetic flux tube embedded in a realistic gravitationally stratified solar atmosphere between the photosphere and the low choromosphere (above β = 1) are performed. Horizontal and vertical velocity field drivers mimic granular buffeting and solar global oscillations. A uniform torsional driver as well as Archimedean and logarithmic spiral drivers mimic observed torsional motions in the solar photosphere. The results are analyzed using a novel method for extracting the parallel, perpendicular, and azimuthal components of the perturbations, which caters to both the linear and non-linear cases. Employing this method yields the identification of the wave modes excited in the numerical simulations and enables a comparison of excited modes via velocity perturbations and wave energy flux. The wave energy flux distribution is calculated to enable the quantification of the relative strengths of excited modes. The torsional drivers primarily excite Alfvén modes (≈60% of the total flux) with small contributions from the slow kink mode, and, for the logarithmic spiral driver, small amounts of slow sausage mode. The horizontal and vertical drivers primarily excite slow kink or fast sausage modes, respectively, with small variations dependent upon flux surface radius.

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Solar Magnetized Tornadoes: Rotational Motion in a Tornado-Like Prominence

Cited by 54 publications

References 27 publications

A solar tornado observed by EIS

A solar tornado observed by EIS

Conversion from mutual helicity to self-helicity observed with IRIS

Generation of Magnetohydrodynamic Waves in Low Solar Atmospheric Flux Tubes by Photospheric Motions

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