Issue |
A&A
Volume 482, Number 2, May I 2008
|
|
---|---|---|
Page(s) | L9 - L12 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20079340 | |
Published online | 19 March 2008 |
Letter to the Editor
Hinode observations of transverse waves with flows in coronal loops
Dept. of Physics, The Catholic University of America and NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771, USA e-mail: ofman@waves.gsfc.nasa.gov
Received:
28
December
2007
Accepted:
12
March
2008
Aims. We report the first evidence for transverse waves in coronal multithreaded loops with cool plasma ejected from the chromosphere flowing along the threads. These observations are good candidates for coronal seismology.
Methods. We analyzed observations made with Solar Optical Telescope (SOT) on board the Hinode satellite in the Ca II H line filter.
Results. The oscillations are visible for about 3 periods, with a period lasting about 2 min, with
weak damping. We see the oscillations in thin threads (~) of
cool plasma flowing in the coronal loops with speeds in the range 74-123 km s-1.
Conclusions. Observations indicate that the waves exhibit different
properties in the various threads. In some threads, the waves are nearly
standing fundamental kink modes with a phase speed of about 1250 km s-1,
whereas the dynamics of other threads is consistent with propagating fast
magnetosonic waves. Based on the observed wave and loop properties and the
assumed active region loop density in the range
109 cm-3,
the estimated energy flux is sufficient to heat the loops to coronal
temperatures, and the average magnetic field in the threads is estimated as
20 ± 7 G.
Key words: Sun: flares / Sun: corona / Sun: magnetic fields / Sun: oscillations / waves
© ESO, 2008
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