The Zeeman-sensitive emission lines of MgI at 12 microns in Procyon

• Emission lines of magnesium at 12 mum have been observed in the spectrum of Procyon. We reproduce the observed disk-averaged line flux from Procyon ( as well as the observed intensity profiles from the Sun) by calculating the line formation and relaxing the assumption of local thermodynamic equilibrium. We find that the lines in Procyon are formed in the photosphere in the same manner as the solar lines. We discuss our modeling of these Rydberg lines and evaluate, among other things, the importance of the ionizing flux and updated model-atom parameters. The lines are of large diagnostic value for measurements of stellar magnetic fields through their Zeeman splitting. We have not, however, detected splitting of the Mg I lines in Procyon. Using simple arguments, we believe that we would have detected a magnetic field had it been of a strength larger than approximately 800 G covering more than a quarter of the surface. We discuss the prospects for future use of the Zeeman-sensitive, mid-infrared Mg I emission lines as a diagnostic tool for stellar magnetic fields.

Nyckelord

infrared : stars

stars : atmospheres

stars : individual (alpha Canis Minoris)

stars : magnetic fields

solar magnetic features

i 12-mu-m diagnostics

infrared lines

non-lte

neutral magnesium

probes

stars

model

transitions

parameters

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)