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A&A Supplement series, Vol. 123, June I 1997, 329-352

Received March 14; accepted September 27, 1996

New ``weak-line"-T Tauri stars in Lupusgiftex2html_wrap_inline1395

J. Krauttertex2html_wrap1415 - R. Wichmanntex2html_wrap1417 - J.H.M.M. Schmitttex2html_wrap1419 - J.M. Alcalátex2html_wrap1421 - R. Neuhäusertex2html_wrap1423 - L. Terranegratex2html_wrap1425

Send offprint request: J. Krautter

tex2html_wrap1427  Landessternwarte Königstuhl, D-69117 Heidelberg, Germany
tex2html_wrap1429  Max-Planck-Institut für Extraterrestrische Physik, D-85740 Garching, Germany
tex2html_wrap1431  Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli, Italy
tex2html_wrap1433  Instituto Nacional de Astrofísica Optica y Electrónica, A.P. 51 y 216, CP 72000, Puebla, México


We present first results obtained by a survey of the Lupus star forming region in search of new T Tauri stars. This study has been performed on the basis of deep pointed ROSAT observations in the Lupus dark clouds as well as data from the ROSAT All-Sky-Survey in the surrounding, less obscured regions. Our survey covers an area of about 230 square degrees, located between tex2html_wrap_inline1397 and tex2html_wrap_inline1399 in right ascension and between tex2html_wrap_inline1401 and tex2html_wrap_inline1403 in declination. Identification of ROSAT All-Sky-Survey sources in this area by means of optical spectroscopy revealed 89 TTauri stars, 86 of them ``weak-line" TTauri stars (WTTS) not known from previous studies of this region. Our pointed ROSAT observations led to the identification of 47 more TTauri stars, giving a total of 136 new TTauri stars. The large area of our study, as compared with previous works, allows us to study the spatial distribution of WTTS in this star forming region on a large scale. We find the new WTTS to be distributed over the whole area of our survey, indicating that their spatial distribution might extend well beyond our study area. Contrary to the Lupus TTauri stars known prior to this study, the WTTS discovered by the ROSAT All-Sky-Survey are not clustered in the regions of highest extinction, i.e. the dark clouds.

keywords: stars: formation -- stars: pre-main sequence -- X-rays: stars -- surveys -- ISM: Lupus clouds

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