EDP Sciences
Free access
Volume 480, Number 2, March III 2008
Page(s) 509 - 514
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20078329

A&A 480, 509-514 (2008)
DOI: 10.1051/0004-6361:20078329

Analysis of the Fe X and Fe XIV line width in the solar corona using LASCO-C1 spectral data

M. Mierla1, 2, R. Schwenn1, L. Teriaca1, G. Stenborg3, and B. Podlipnik1

1  Max-Planck-Institut für Sonnensystemforschung 37191 Katlenburg-Lindau, Germany
    e-mail: m_mierla@yahoo.co.uk
2  Astronomical Institute of the Romanian Academy, Bucharest, Romania
3  Catholic University of America, Washington DC 20064, USA

(Received 21 July 2007 / Accepted 20 November 2007)

Aims.The purpose of this paper is to analyze the variation in the line width with height in the inner corona (region above 1.1 $R_{\odot}$), by using the spectral data from LASCO-C1 aboard SOHO. We used data acquired at activity minimum (August-October 1996) and during the ascending phase of the solar cycle (March 1998).
Methods.Series of images acquired at different wavelengths across the Fe X 637.6 nm (red) and Fe XIV 530.3 nm (green) coronal lines by LASCO-C1 allowed us to build radiance and width maps of the off-limb solar corona.
Results.In 1996, the line width of Fe XIV was roughly constant or increased with height up to around 1.3 $R_{\odot}$ and then it decreased. The Fe X line width increased with height up to the point where the spectra were too noisy to allow line width measurements (around 1.3 $R_{\odot}$). Fe X showed higher effective temperatures as compared with Fe XIV. In 1998 the line width of Fe XIV was roughly constant with height above the limb (no Fe X data available).

Key words: Sun: corona -- lines: profiles -- Sun: atmosphere

© ESO 2008

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