SCYON Abstract

Received on October 21 2002

Observational clues for a role of circumstellar accretion in PMS X-ray activity

Authors	E. Flaccomio, G. Micela, S. Sciortino
Affiliation	INAF - Osservatorio Astronomico di Palermo G.S. Vaiana, Palazzo dei Normanni, I-90134 Palermo, Italy
Accepted by	Astronomy & Astrophysics
Contact	ettoref@oapa.astropa.unipa.it
URL	http://www.astropa.unipa.it/Library/preprint.html
Links	Orion \| NGC 2264

Abstract

We revisit the published analyses of ROSAT X-ray observations of the star forming regions NGC 2264 and Chamaeleon I (~3 and ~5 Myr old respectively) in the light of newly published optical data. At odds with previous results on Chamaeleon I members, we find that low mass stars in both regions have near-saturated emission levels. Similarly to what previously found in the Orion Nebula Cluster, Weak Line T-Tauri Stars in NGC 2264 and in the Chamaeleon I cloud have higher X-ray activity levels respect to Classical T Tauri Stars, arguing in favor of a role of the disk and/or accretion in determining X-ray emission.