This is all long before their nuclear furnaces of hydrogen even ignite, the mark of stellar maturity. The X-ray flares have also provided the closest look yet at the youngest stars in the Universe, never before detected because they are hidden within dust and molecular clouds that filter all other types of light. With Chandra, we now have a new tool to examine protostars, which have been impossible to gain access to in any other wavelength.
Red color represents less absorbed X rays, while blue represents absorbed X rays.
Lightcurves for each sources are also shown. The transition from one class to another is marked by changes in the protostar's infrared spectrum as the gas and dust envelope diminishes. The envelope has been well studied by infrared and radio astronomers. Protostars themselves and their most extreme activities, however, have remained hidden until now, embedded in the dense envelopes. These satellites did not have enough spatial resolution nor sensitivity, however, to resolve the large percentage of protostars deep inside crowded cloud cores.