Thomas Preibisch
X-ray Activity and Accretion in Young Stellar Objects
(Invited Review Talk) International Workshop
Magnetic fields and star formation: theory versus observations,
Madrid, (Spain), April 21 - 25, 2003
Proceedings to be published by Kluwer Adad. Publ., Dordrecht (2003)
Abstract.
I discuss recent observational results on the X-ray properties
of young stellar objects, based mostly on Chandra and XMM-Newton
observations. The sensitive X-ray data on large, well characterized
samples of T Tauri stars (and protostars) allow to study in detail the
dependence of magnetic activity on the bulk properties of the young objects
and to draw important clues towards the origin of the X-ray emission.
The absence of a relation between X-ray activity and
rotation for T Tauri stars clearly suggests that their magnetic activity
cannot be simply explained by the action of a scaled-up solar-like dynamo.
I discuss alternative models for the generation of magnetic fields
and also consider the long standing question whether the X-ray
properties of the T Tauri stars are related to the presence/absence of
circumstellar disks or active accretion.