SIMBAD references

New theoretical data for calculating the widths and shifts of solar high-l Rydberg lines of neutral magnesium are reported. The line shifts measured by Chang & Schoenfeld (1991) have been reanalysed to obtain mean values of the electron densities in the regions where the lines are formed. lt is found that, on the assumption that the shifts due to interaction with neutral hydrogen atoms are negligible, the lines are formed in a photospheric layer of about 200 km thick, at heights between 150 and 350 km, and electron densities between 1.5 10¹² and 6.6 10¹² cm^–3.