Measurements of Zeeman broadening in F, G, and K dwarfs.

Zeeman broadening was detected and measured in the spectra of seven out of a sample of 18 F, G, and K dwarfs. All of the sample from G6 V and cooler show magnetic fields, typically 1.9 kilogauss; almost none earlier did. The analysis employs the leverage of many spectral lines used directly in the Fourier transform domain. In the F, G, and K dwarfs, the Zeeman broadening is often small compared to the Doppler broadening of rotation and turbulence. In such cases it is difficult to separate the strength of the field from the fraction of the stellar disk covered by field; it is impractical to seek a distribution of field strengths. Several limitations and systematic errors are considered.