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Astronomy & Astrophysics manuscript no. Ban12242 c ESO 2009 June 18, 2009
 

Summary: Astronomy & Astrophysics manuscript no. Ban12242 c ESO 2009
June 18, 2009
LETTER TO THE EDITOR
Signatures of Alfven waves in the polar coronal holes as seen by
EIS/Hinode
D. Banerjee1, D. Perez-Suarez2, and J.G. Doyle2
1
Indian Institute of Astrophysics, Bangalore 560034, India
2
Armagh Observatory, College Hill, Armagh BT61 9DG, N.Ireland
ABSTRACT
Context. We diagnose the properties of the plume and interplume regions in a polar coronal hole and the role of waves in the
acceleration of the solar wind.
Aims. We attempt to detect whether Alfven waves are present in the polar coronal holes through variations in EUV line widths.
Methods. Using spectral observations performed over a polar coronal hole region with the EIS spectrometer on Hinode, we study the
variation in the line width and electron density as a function of height. We use the density sensitive line pairs of Fe XII 186.88 &
195.119 and Fe XIII 203.82 & 202.04 .
Results. For the polar region, the line width data show that the nonthermal line-of-sight velocity increases from 26 km s-1
at 10
above the limb to 42 km s-1

  

Source: Armagh Observatory

 

Collections: Physics