1. The observed X-ray coronal line ratios O vii (f+i)/r (G ratio) versus O vii f/i (R ratio), overlaid with curves of constant ionization parameter (log U = −1, −0.5, 0, …, 2) for two constant number densities (ne = 103 cm−3 and ne = 1012 cm−3) and a fixed column density of NH = 1021 cm−2, assuming photoionization equilibrium.
The observed X-ray coronal line ratios O vii (f+i)/r (G ratio) versus O vii f/i (R ratio), overlaid with curves of constant ionization parameter (log U = −1, −0.5, 0, …, 2) for two constant number densities (ne = 103 cm−3 and ne = 1012 cm−3) and a fixed column density of NH = 1021 cm−2, assuming photoionization equilibrium. The case of collisional ionization equilibrium is shown in green. We plot 1σ error bars.
Hermine Landt et al. MNRAS 2015;449:
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society