On the widths of the Mg X lines near 60 nm in the corona

¹ Max-Planck-Institut für Aeronomie, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany
² Department of Applied Physics, Banaras Hindu University, Varanasi-221005, India

Corresponding author: K. Wilhelm, wilhelm@linmpi.mpg.de

Received: 27 August 2003
Accepted: 3 November 2003

Abstract

We examine the line widths of both components of the Mg x doublet at 60.98 nm and 62.50 nm in the low corona of the quiet Sun, and find that the Doppler width (i.e. half width) broadens from  pm to ≈9.5 pm (with an estimated relative standard uncertainty of 4%) between the limb and 220 Mm above the limb in the equatorial corona. In a polar coronal hole, the Doppler width increases from 10.8 pm near 30 Mm to 11.4 pm at around 80 Mm. The analysis does not provide any evidence for a narrowing of the emission-line profiles as a function of the distance from the solar limb.