Rossby number calculations for fully convective stars

The Rossby number is a quantity that gauges the relative importance of
rotation in astrophysical flows. In particular, it plays a significant role
in mean-field, alpha-Omega dynamo models as it is directly related to the
“dynamo number” which, in turn, measures the efficiency of the magnetic field
generation. From an observational standpoint, the Rossby number has been
widely used to correlate either coronal or chromospheric magnetic activity of
low-mass stars with their rotation. A fundamental problem with this
rotation-activity relationship is the determination of the convective turnover
time tau_c, on which the Rossby number depends, and that can be obtained
from some empirical relations or from stellar models. The ATON stellar
evolution code has been used in the near past to calculate Rossby numbers
for solar-type stars and now, in view of the recent discovery of fully
convective stars in the non-saturated region of the rotation-activity
relationship, is being used to extend those calculations to very low mass
stars.