Published online by Cambridge University Press: 12 April 2016
X-ray spectra of stellar X-ray sources taken with high, moderate and low spectral resolution are discussed. Only low resolution spectra are available for a sufficiently large number of late-type stars. It is shown that high temperature plasmas (log T > 7) produce the dominant emission component in the coronae of red dwarfs as well as yellow giants, while the coronae of F stars – usually – have X-ray temperatures similar to those found in the quiet Sun. The need for density diagnostics of stellar coronae is stressed and it is argued that the waveband region between 90 – 140 Å is particularly well suited for this purpose.