dc.contributor.author |
Banerjee, D |
|
dc.contributor.author |
O'Shea, E |
|
dc.contributor.author |
Doyle, J. G |
|
dc.date.accessioned |
2009-06-04T10:44:46Z |
|
dc.date.available |
2009-06-04T10:44:46Z |
|
dc.date.issued |
2005-12 |
|
dc.identifier.citation |
D. Danesy, S. Poedts, A. De Groof and J. Andries., eds., Proceedings of the 11th European Solar Physics Meeting "The Dynamic Sun: Challenges for Theory and Observations" (ESA SP-600). 11 - 16 September 2005, pp. 43 - 48 |
en |
dc.identifier.issn |
92-9092-911-1 |
|
dc.identifier.uri |
http://hdl.handle.net/2248/4510 |
|
dc.description.abstract |
Using measurement from the Coronal Diagnostic Spectrometer (CDS) on board SOHO we seek to examine the relative roles of radiative and Collisional excitation in regions far off-limb at the Northern pole of the sun. We study the line width variation with height. It is found that above 1150 arcsec the second ratio of two coronal Mg X resonance lines reduces to values that we might expect for a radiatively dominant excitation mode. A comparison of line widths with the Mg X ratios shows that the line widths start to show a decrease in their values at the same location where the dominant excitation changes from being collisionally to radiatively dominant. This is considered to be evidence for a sudden drop in the electron density at this location, and, therefore, the reported tributed to a reduction in the measurable contribution of waves/turbulence to the non-thermal velocity component of the line widths. This result suggests that the reported decrease of line widths in coronal ions at large altitudes off-limb may not simply be related to the dissipation of wave energy. Implication to the acceleration of the fast solar wind will be discussed. |
en |
dc.language.iso |
en |
en |
dc.publisher |
European Space Agency |
en |
dc.relation.uri |
http://adsabs.harvard.edu/abs/2005ESASP.600E..43B |
en |
dc.subject |
Polar Off-Limb Regions |
en |
dc.subject |
Dynamic Sun |
en |
dc.subject |
Observations |
en |
dc.subject |
Solar Physics |
en |
dc.title |
Variation of line widths in polar off-limb regions |
en |
dc.type |
Article |
en |