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Issue A&A
Volume 431, Number 3, March I 2005
Page(s) L17 - L20
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200400137



A&A 431, L17-L20 (2005)
DOI: 10.1051/0004-6361:200400137

Letter

Line broadening of EUV lines across the Solar limb: A spicule contribution?

J. G. Doyle1, J. Giannikakis1, 2, L. D. Xia1, 3 and M. S. Madjarska4, 5

1  Armagh Observatory, College Hill, Armagh, BT61 9DG, N. Ireland
    e-mail: jgd@arm.ac.uk, http://star.arm.ac.uk/preprints/
2  Sect. of Astrophysics, Astronomy and Mechanics, Dept. of Physics, Univ. of Athens, Athens 15783, Greece
3  School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, PR China
4  Max-Planck-Institut für Sonnensystemforschung (Former Max-Planck-Institut für Aeronomie.) , Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany
5  Department of Solar Physics, Royal Observatory of Belgium, Av. Circulaire 3, 1180 Bruxelles, Belgium

(Received 20 December 2004 / Accepted 28 December 2004)

Abstract
Spectral lines formed in the solar transition region show an increase in the line width, peaking at $\approx$10 000 km above the limb. Looking at a region off-limb with no obvious spicules, the non-spicule region has a significantly smaller line width above 6000 km compared those taken in a spicule region. We suggest that this increase in line broadening is not due to small scale random motions but rather to unresolved line shifts due to spicules and/or macro-spicules activity.


Key words: Sun: atmosphere -- transition region -- off-limb -- line broadening -- spicules




© ESO 2005

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