this discrepancy to a deviation of the electron and the ion temperatures. Finally, we have found that the outflow speeds studied in the O[vi]{} line in the plumes corrected by the angle between the line of sight and the plume orientation are quite small with a maximum of 10 $\mathrm{km~s^{-1}}$. It is unlikely that plumes are a dominant contributor to the fast solar wind.'
author:
- 'L. [Feng]{}, B. [Inhester]{}, S.K. [Solanki]{}, K. [Wilhelm]{}, T. [Wiegelmann]{}, B. [Podlipnik]{}, R.A. [Howard]{}, S.P. [Plunkett]{}, J.P. [Wuelser]{},and W.Q. [Gan]{}'
title: 'Stereoscopic polar plume reconstructions from STEREO/SECCHI images'
---

Introduction
============

With the launch of NASA’s *STEREO* mission in October 2006, a new dimension has been added to solar coronal observations. The two spacecraft orbit the Sun and separate slowly in longitude by about $45^{\circ}$ per year. The first year after launch is the best time for the 3D reconstruction of coronal structures, such as magnetic loops [@Wiegelmann:Inhester:2006; @Feng:etal:2007a; @Feng:etal:2007b; @Aschwanden:etal:2008a], polar plumes [@Curdt:etal:2008], polar jets [@Patsourakos:etal:2008], solar prominences (filaments), etc., which can be achieved by analysing the image pairs taken by the EUVI telescopes that are part of the SECCHI suite of imagers. EUVI is very similar to EIT/*SOHO*, but with higher spatial 