Pre-main sequence stars masses

We benchmark pre-main sequence stellar evolutionary tracks using stellar masses dynamically estimated by fitting a parametric model to ALMA observations of the ^12^CO (J=3-2) line transition emitted by the disks orbiting 20 sources in the old (4-14Myr) Upper Scorpius star forming region.

We derive stellar masses from HR diagram fitting for ten different stellar evolutionary models, which we then compare with their stellar dynamical masses for comparison in the stellar mass range 0.1-1.3M_{sun}_. Models with a moderate-to-low fraction of cold stellar spots (f=17%) most accurately reproduce the dynamical stellar masses (100% of the targets agree within +/-1{sigma}). While a higher spot coverage (f=34%) provides similar stellar mass predictions similar to magnetic equipartition models, larger fractions (f>=51%) significantly disagree with dynamical masses.