Fig. 2: Phase-folded mean longitudinal magnetic field strengths in the photospheres and chromospheres.
From: Measuring the magnetic fields in the chromospheres of low-mass stars
a AD Leo. b YZ CMi. c EV Lac. a–c The rotational phases were derived from the same ephemera. Red triangles are photospheric fields 〈Bp〉 inferred from LSD profiles; yellow squares are lower chromospheric fields 〈BcL〉 from Hα, blue pentagons are middle chromospheric fields 〈BcM〉 from Ca IRT. Filled markers are taken from a marked epoch with full phase coverage for each star. For these epochs, the linear Pearson correlation coefficients between the field strengths of two layers are also listed in the left block. For each marked epoch, we give a two-harmonic Fourier series to fit the pattern, showing the periodic signal of the magnetic field variation.
