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Author Doyle, J. G. ♦ Teriaca, L. ♦ Banerjee, D.
Source CiteSeerX
Content type Text
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Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Subject Keyword Solar Transition Region Line Broadening ♦ Limb Measurement ♦ Line Width ♦ Transition Region ♦ Temperature Ne Viii Line ♦ Opacity Effect ♦ Center-to-limb Variation ♦ Probable Explanation ♦ Disk Center ♦ Slower Variation ♦ Full Disk Image ♦ Sumer Soho ♦ Mass Motion ♦ Vertical Plane ♦ Upper Chromosphere ♦ Non-thermal Motion ♦ Horizontal Unresolved Motion ♦ Km Gamma1 Difference ♦ Ne Viii
Abstract . Full disk images from SUMER/SoHO taken in He i, C iv and Ne viii are used to investigate whether there exists a center-to-limb variation in the line width. Both C iv and He i show such a variation but the higher temperature Ne viii line is relatively constant. For C iv, this corresponds to 3 km s \Gamma1 difference while He i is significantly larger particularly at the limb. This work may suggest that the non-thermal motions are slightly nonisotropic in the transition region and upper chromosphere, with the horizontal unresolved motions exceeding those in the vertical plane however a more probable explanation is that the lines are broadened due to opacity effects. The more slower variation in the C iv 1548 A line width could be explained by increasing the opacity from zero at disk center to 1 at the limb. For He i the opacity is significantly grater than unity at the limb. This therefore implying all mass motions in the chromosphere, transition region and corona are isotropic. Ke...
Educational Role Student ♦ Teacher
Age Range above 22 year
Educational Use Research
Education Level UG and PG ♦ Career/Technical Study