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Astronomy & Astrophysics manuscript no. bpdensref March 16, 2005 (DOI: will be inserted by hand later)

Summary: Astronomy & Astrophysics manuscript no. bpdens—ref March 16, 2005
(DOI: will be inserted by hand later)
Research Note
Electron densities in EUV coronal bright points
I. Ugarte­Urra 1 , J. G. Doyle 1 , and G. Del Zanna 2
1 Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
2 Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
Received / Accepted
Abstract. Electron density measurements of six coronal bright points have been obtained using line ratio diagnostics of four
ions in the temperature range 1.3--2.0×10 6 K. The results suggest that BP plasma has more similarities to active region plasma
than to quiet Sun plasma. Nevertheless, they do not show the exact same behaviour: the increase of electron density at temper­
atures over log T e # 6.2, observed in the core of active regions, has not been detected. The Fe ### results based on new atomic
data, although in better agreement decreasing more than a factor of two the densities obtained with older calculations, are still
in some instances higher than those from Si #. This could be a consequence of the inhomogeneity of the plasma in the observed
volume. New measurements with a better constriction of the volumetric properties seem necessary to rule out the influence of
other factors and confirm whether there is an inconsistency between the ions, perhaps due to line blending problems in the Fe ###
Key words. Sun: corona -- Sun: fundamental parameters -- Hydrodynamics
1. Introduction
Determining properties like the electron density, temperature,


Source: Armagh Observatory


Collections: Physics