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Astron. Astrophys. 320, 185-195 (1997)


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The T Tauri star population in the Lupus star forming region * **

R. Wichmann 1, J. Krautter 1, E. Covino 2, J.M. Alcalá 3, 4, R. Neuhäuser 3 and J.H.M.M. Schmitt 3

1 Landessternwarte Königstuhl, D-69117 Heidelberg, Germany
2 Osservatorio Astronomico di Capodimonte, Napoli, Italy
3 Max-Planck-Institut für Extraterrestrische Physik, D-85740 Garching, Germany
4 Instituto Nacional de Astrofisica Optica y Electrónica, A.P. 51 y 216, CP 72000, Puebla, México

Received 25 April 1996 / Accepted 26 September 1996

Abstract

In a recent study, some 130 new weak-line T Tauri stars (WTTS) have been discovered in the Lupus star forming region (SFR). Some of these stars are seen projected onto regions of high obscuration, while others are located far from the Lupus dark clouds. In this paper we present photometric observations of a large sample of these WTTS. We estimate effective temperatures and luminosities for the stars observed, and derive masses and ages by comparison with theoretical evolutionary tracks. The mean age of WTTS seen in projection against the dark clouds is found to be lower than the mean age of WTTS discovered far from regions of high obscuration, and yet higher than the mean age of the classical T Tauri stars (CTTS) in Lupus. Moreover, while the CTTS in Lupus show an unusual predominance of very low-mass stars, the WTTS population in Lupus contains many stars with comparatively higher masses. Correlations between the X-ray emission and other stellar parameters, like bolometric luminosity, radius, mass, and age, are studied, and the results are discussed.

Key words: stars: formation – stars: late-type – stars: pre-main sequence – X-rays: stars

* Based on observations collected at European Southern Observatory, Chile (observing proposals ESO [FORMULA] 50.7-0110, 53.7-0085).
** Tables 6 and 7 are only available in electronic form at the CDS via anonymous ftp 130.79.128.5.

Send offprint requests to: R. Wichmann

© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998

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