Multi-wavelength spectroscopic observation of EUV jet in AR 10960

We have studied the relationship between the velocity and temperature of a solar EUV jet. The highly accelerated jet occurred in the active region NOAA 10960 on 2007 June 5. Multi-wavelength spectral observations with EIS/Hinode allow us to investigate Doppler velocities at the wide temperature range. We analyzed the three-dimensional angle of the jet from the stereoscopic analysis with STEREO. Using this angle and Doppler velocity, we derived the true velocity of the jet. As a result, we found that the cool jet observed with \ion{He}{2} 256 \AA $\log_{10}T_e[\rm{K}] = 4.9$ is accelerated to around $220 \rm{km/s}$ which is over the upper limit of the chromospheric evaporation. The velocities observed with the other lines are under the upper limit of the chromospheric evaporation while most of the velocities of hot lines are higher than that of cool lines. We interpret that the chromospheric evaporation and magnetic acceleration occur simultaneously. A morphological interpretation of this event based on the reconnection model is given by utilizing the multi-instrumental observations.Comment: Accepted for publication in Ap

Identification of different types of kink modes in coronal loops: principles and application to TRACE results

We explore the possible observational signatures of different types of kink modes (horizontal and vertical oscillations in their fundamental mode and second harmonic) that may arise in coronal loops, with the aim of determining how well the individual modes can be uniquely identified from time series of images. A simple, purely geometrical model is constructed to describe the different types of kink-mode oscillations. These are then `observed' from a given direction. In particular, we employ the 3D geometrical parameters of 14 TRACE loops of transverse oscillations to try to identify the correct observed wave mode. We find that for many combinations of viewing and loop geometry it is not straightforward to distinguish between at least two types of kink modes just using time series of images. We also considered Doppler signatures and find that these can help obtain unique identifications of the oscillation modes when employed in combination with imaging. We then compare the modeled spatial signatures with the observations of 14 TRACE loops. We find that out of three oscillations previously identified as fundamental horizontal mode oscillations, two cases appear to be fundamental vertical mode oscillations (but possibly combined with the fundamental horizontal mode), and one case appears to be a combination of the fundamental vertical and horizontal modes, while in three cases it is not possible to clearly distinguish between the fundamental mode and the second-harmonic of the horizontal oscillation. In five other cases it is not possible to clearly distinguish between a fundamental horizontal mode and the second-harmonic of a vertical mode.Comment: 12 pages, 10 figures, 2 tables. A&A in pres

Excitation of standing kink oscillations in coronal loops

In this work we review the efforts that have been done to study the excitation of the standing fast kink body mode in coronal loops. We mainly focus on the time-dependent problem, which is appropriate to describe flare or CME induced kink oscillations. The analytical and numerical studies in slab and cylindrical loop geometries are reviewed. We discuss the results from very simple one-dimensional models to more realistic (but still simple) loop configurations. We emphasise how the results of the initial value problem complement the eigenmode calculations. The possible damping mechanisms of the kink oscillations are also discussed

Structural variety of developing and equilibrium horizontal convection confined in a rectangular vessel resulting from different heating plate arrangements

Flow structures formed in a rectangular fluid layer with an aspect ratio of four driven by a horizontal temperature gradient along the top boundary, so-called horizontal convection in both developing and equilibrium cases, were investigated via flow visualization using thermochromic liquid crystal microcapsules. Four separated heating panels on the top of the vessel allowed the influence of the heating plate arrangement on the determination of the flow structure to be examined. The velocity vector fields averaged in local space and time showed that the flow structures in the developing cases with an initial stable temperature stratification consisted of shallow circulation beneath the top boundary, with the time development of the structures being independent of the plate arrangement. The number of circulations along the top boundary is associated with locations having horizontal temperature gradients. In the equilibrium state, however, the flow structures are more complex because of the influence of the unstable temperature stratification, which is modified by the circulation

Structural variety of developing and equilibrium horizontal convection confined in a rectangular vessel resulting from different heating plate arrangements

Flow structures formed in a rectangular fluid layer with an aspect ratio of four driven by a horizontal temperature gradient along the top boundary, so-called horizontal convection in both developing and equilibrium cases, were investigated via flow visualization using thermochromic liquid crystal microcapsules. Four separated heating panels on the top of the vessel allowed the influence of the heating plate arrangement on the determination of the flow structure to be examined. The velocity vector fields averaged in local space and time showed that the flow structures in the developing cases with an initial stable temperature stratification consisted of shallow circulation beneath the top boundary, with the time development of the structures being independent of the plate arrangement. The number of circulations along the top boundary is associated with locations having horizontal temperature gradients. In the equilibrium state, however, the flow structures are more complex because of the influence of the unstable temperature stratification, which is modified by the circulation