EDP Sciences
Free access
Issue
A&A
Volume 378, Number 1, October IV 2001
Page(s) 257 - 265
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20011231


A&A 378, 257-265 (2001)
DOI: 10.1051/0004-6361:20011231

Dopplershifts in the solar transition region

C. Gontikakis1, H. C. Dara1, C. E. Alissandrakis2, Th. G. Zachariadis1 and J.-C. Vial3

1  Research Center for Astronomy and Applied Mathematics, Academy of Athens, 14 Anagnostopoulou St., 10673 Athens, Greece
2  Section of Astro-Geophysics, Department of Physics, University of Ioannina, 45110 Ioannina, Greece
3  Institut d'Astrophysique Spatiale, Unité Mixte CNRS-Université Paris XI, Bât. 121, 91405 Orsay, France

(Received 13 April 2000 / Accepted 28 August 2001 )

Abstract
We study the dynamics of the quiet sun transition region, using observations obtained with the SOHO CDS/NIS and SUMER spectrographs. We examine the morphology of the network as a function of temperature and we compare the intensity features with those of the dopplergrams. The velocity distributions have a different behaviour for the bright features which outline the network and the dark ones, located in the internetwork. A redshift and a smaller standard deviation are observed for the bright feature distributions relative to the dark ones. It should be mentioned that the internetwork is also statistically redshifted, with the exception of the He I line. Velocity distributions from different lines are compared.


Key words: Sun: transition region -- line formation

Offprint request: C. Gontikakis, cgontik@cc.uoa.gr




© ESO 2001