|
The HETG Orion Legacy project aims to study plasma properties of a large number of highly resolved X-ray spectra from young stars over a large range of masses and evolutionary stages.
The HETG spectra are collected throughout the lifetime of Chandra and thus not only provide highly significant X-ray line strengths for detailed plasma diagnostics but also longterm X-ray monitoring. The heart of the Orion Nebula Cluster with a dynamic age of ~3x10^5 yr is one of the youngest and closest star forming regions to our Sun and contains an ensemble of the youngest massive and intermediate mass stars we know in the Galaxy. Three out of at least four of the most massive ZAMS stars, Theta1 Ori A, C and Theta2 Ori A show coronal properties indicative of magnetic activity that is very likely not due to existing or unseen low-mass PMS companions. Theta1 Ori E, now identified as an intermediate mass PMS binary, is the
second most luminous X-ray source in the ONC, and shows very high persistent X-ray temperatures and high plasma densities which are quite unusual properties in comparison with the
coronal activities observed in low-mass PMS stars in the neighborhood. The Orion properties are compared
with the ones so far observed in several other young massive cluster cores and discussed in the context of
early stellar evolution.
|