Recent observations of rapidly-rotating cool dwarfs have revealed Hα
line asymmetries indicative of clumps of cool, dense plasma in the stars'
coronae. These clumps may be either long-lived (persisting for more than one
stellar rotation) or dynamic. The fastest dynamic features show velocities
greater than the escape speed, suggesting that they may be centrifugally
ejected from the star, contributing to the stellar angular momentum loss. Many
however show lower velocities, similar to coronal rain observed on the Sun. We
present 2.5D magnetohydrodynamic simulations of the formation and dynamics of
these condensations in a rapidly rotating (Prot​ = 1 day)
young Sun. Formation is triggered by excess surface heating. This pushes the
system out of thermal equilibrium and triggers a thermal instability. The
resulting condensations fall back towards the surface. They exhibit
quasi-periodic behaviour, with periods longer than typical periods for solar
coronal rain. We find line-of-sight velocities for these clumps in the range
50 km s−1 (blue shifted) to $250 \ \mathrm{km} \
\mathrm{s}^{-1}(redshifted).ThesearetypicalofthoseinferredfromstellarH\alphalineasymmetries,buttheinferredclumpmassesof3.6\times
10^{14}\ \mathrm{g}aresignificantlysmaller.Wefindthatamaximumof\simeq~3\%$ of the coronal mass is cool clumps. We conclude that coronal rain
may be common in solar like stars, but may appear on much larger scales in
rapid rotators.Comment: 11 pages, 5 figure