Intensity and Doppler Velocity Oscillations in Pore Atmospheres |
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Kyung-Suk Cho Submitted: 2015-03-27 03:30
We have investigated chromospheric traveling features running across two merged pores from their centers at speeds of about 55 km s-1, in the active region AR 11828. The pores were observed on 2013 August 24 by using high-time, spatial, and spectral resolution data from the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope. We infer a line-of-sight (LOS) velocity by applying the lambdameter method to the Ca ii 8542 Å band and Hα band, and investigate intensity and LOS velocity changes at different wavelengths and different positions at the pores. We find that they have three-minute oscillations, and the intensity oscillation from the line center (0.0 Å ) is preceded by that from the core (-0.3 Å ) of the bands. There is no phase difference between the intensity and the LOS velocity oscillations at a given wavelength. The amplitude of LOS velocity from the near core spectra (Δλ =0.10-0.21 Å ) is greater than that from the far core spectra (Δλ =0.24-0.36 Å ). These results support the interpretation of the observed wave as a slow magnetoacoustic wave propagating along the magnetic field lines in the pores. The apparent horizontal motion and a sudden decrease of its speed beyond the pores can be explained by the projection effect caused by inclination of the magnetic field with a canopy structure. We conclude that the observed wave properties of the pores are quite similar to those from the sunspot observations.
Authors: Cho, K.-S., Bong, S.-C., Nakariakov, V. M., Lim, E.-K., Park, Y.-D., Chae, J. C., Yang, H.-S., Park, H.-M., Yurchyshyn, V.
Projects: Other
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Publication Status: ApJ (published)
Last Modified: 2015-03-27 14:08
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