Publications
of the
MPIfR Optical & Infrared Interferometry Group

T. Preibisch

The coronae of very young solar-like stars

In: Schielikke, R.E. (ed.): Short Contrib. Ann. Sci. Meeting Astron. Ges. Freiburg 2003. Astron. Nachr. 324, Suppl. Issue 3 (2003), 17
The Sun and Planetary Systems - Paradigms for the Universe
Annual Scientific Meeting of the Astronomische Gesellschaft, Sep 15-20, 2003, Freiburg, Germany

Abstract

Very young solar-like stars (T Tauri Stars) show generally very high levels of X-ray activity. Their X-ray luminosities are elevated by factors up to ~ 10 4 times, their coronal plasma temperatures up to ~ 30 times over the solar values. The origin of this strong X-ray activity is still not well understood.

The Chandra and XMM-Newton observatories have recently provided very sensitive X-ray data on large, well characterized samples of T Tauri stars, which allow to study in detail the dependence of magnetic activity on the bulk properties of the young stars and to draw important clues towards the origin of the X-ray emission. A particularly important recent result is the absence of a relation between X-ray activity and rotation for T Tauri stars, which clearly suggests that their magnetic activity cannot be simply explained by the action of a scaled-up solar-like dynamo.

I will introduce the "Chandra Orion Ultradeep Project", in which an 850 ksec (i.e. 10 full days!) exposure of the Orion Nebula Cluster was recently obtained with the ACIS camera, by far the deepest and most sensitive X-ray observation ever obtained for a young cluster. This unique data set allows an investigation of the relations between X-ray activity and stellar properties of young stars in an unprecedented way and will provide a big step forward in our understanding of their X-ray activity.