The Mg I b triplet and the 4571 Å line as diagnostics of stellar chromospheric activity

Abstract

Context. The Mg I 4571 Å line and the b triplet are denoted in the literature as diagnostics of solar and stellar activity since their formation is in the low chromosphere. Aims: We aim to investigate the potential of these four spectral lines as diagnostics of chromospheric activity in solar-like stars, studying the dependence of the intensity of these lines from local atmospheric changes by varying atmospheric models and stellar parameters. <BR /> Methods: Starting with Next-Gen photospheric models, we build a grid of atmospheric models including photosphere, chromosphere and transition region and solve the radiative transfer to obtain synthetic profiles to compare with observed spectra of main-sequence, solar like stars with effective temperatures in the range 4800-6400 K, solar gravity and solar metallicity. Results: We find that the Mg I 4571 Å line is significantly sensitive to local changes in the atmospheric model around the minimum temperature. Conversely, the lines of the b triplet do not show significant responses to changes on the local atmospheric structure.