Pre-main sequence low mass stars have X-ray emission 2-4 orders of magnitude greater than main sequence stars. This emission is thought to arise from enhanced solar--like activity including coronae and flares. The bulk of the pre-main sequence stars observed in X-rays are G, K and early M stars. Such bright emission can be used to identify young stars in the absence of other indication of youth such as a disk. The coronal enhancements are thought to come from a rotational dynamo. High mass stars have a different emission mechanism stemming from their winds and can fill huge volumes of space, parsecs on a side, with extremely hot (10MK), X-ray emitting, plasma.
We use X-ray studies of regions of star formation in embedded clusters as part of an observatory wide program. The X-rays from young stars penetrate gas and dust. This allows us to see stars in their earliest stages as they are being built up. Infrared observations also allow us to see stars and their disks through their natal phases. Combining the observations allows us to study the survival time of planet forming disks around young stars. Studies of older clusters allows us to investigate how the stars effect planets in the earliest stages of planet formation. Some of the stars produce flares so large that they may reach into the surrounding disk disturbing embryonic planets.
Scott Wolk, Nancy Evans, Nancy Brickhouse, Vinay Kashyap, Jeremy Drake