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   PR # 42010
   Recent ROSAT and ASCA observations of molecular clouds have shown
   that X-rays are produced during the earliest phases of stellar
   evolution. Whereas X-ray emission from T Tauri stars is
   well-explained by solar-type magnetic activity, the high energy (1-10
   keV) radiation from cool protostars is remarkable and enigmatic. We
   seek insight into the onset and evolution of protostellar X-ray
   emission, with targets ranging from the youngest Class 0 stars to
   older Class I/II stars. We select four fields with containing nearby,
   well-separated and luminous protostars. This program requires ASCA's
   unique capability to image X-rays through heavy extinction.
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