A ROSAT pointed observation of the Chamaeleon II dark cloud

A deep 13.5 ksec ROSAT PSPC pointed observation in the Chamaeleon II (Cha I I) cloud is reported. 40 X-ray sources are detected of which 14 can be iden tified with previously known young stellar objects (YSOs), namely IRAS sour ces, classical T Tauri stars and weak T Tauri stars. From spectroscopic fol lowup observations, four new weak T Tauri candidates have been found. The X -ray sources are mainly located on the north-east of the cloud and their sp atial distribution follows the lanes of the 100 mu m dust emission. Their X -ray properties are similar to those of low-mass PMS stars. None of the pro tostar candidates in Cha II has been detected in the ROSAT pointed observat ion, in agreement with the ASCA observations results. The X-ray detection r ates indicate that the weak T Tauri stars (WTTS) are less numerous than the classical T Tauri stars (CTTS), contrarily to the findings in Chamaeleon I (Cha I) and other star forming regions where the WTTS may outnumber the CT TS. The latter result could be a consequence of the fact that Cha II is in an earlier evolutionary stage as compared to Cha I, as conjectured by previ ous studies. The Cha II young stellar objects (YSOs) are, on the average, s lightly less X-ray luminous than those in Cha I, but the normalised X-ray l uminosity distribution functions of the two regions are not significantly d ifferent.