Abstract :
X-ray observations have shown that, like all late-type stars, young, low-mass stars are magnetized. X-ray flaring characteristics suggest that the resulting activity is solar-like, with X-ray emission coming from a hot plasma confined in large, reconnecting magnetic loops. On the other hand, except at late stages of their pre-main sequence evolution, young stars are surrounded by circumstellar material, disks and outflows. This review describes current theoretical ideas in which the magnetic field, in particular in the star-disk region, converts accretion from the disks into outflow ejection, and how some theories allow us to predict X-rays from reconnection-induced plasma heating. However, the search for direct X-ray evidence of star-disk interactions, as a partial test of accretion-ejection models, remains so far inconclusive. Accretion disks may play a role in the coronal activity of young stars, but this activity seems to be largely dominated by their solar-like, convection driven, magnetic activity.
