The short period multiplicity among T Tauri stars ^*

European Southern Observatory, Casilla 19001, Santiago 19, Chile Observatoire de Genève, Ch. des Maillettes 51, 1290 Sauverny, Switzerland

Corresponding author: cmelo@eso.org

Received: 11 December 2002
Accepted: 30 July 2003

Abstract

We present the results of high-resolution spectroscopic observations carried out over three years aimed at estimating the short-period ( days) binary frequency of a sample of T Tauri stars in Oph-Sco, Cha, Lup, CrA star forming regions (SFRs), already observed with high angular resolution techniques by Ghez et al. ([CITE]) and by Ghez et al. ([CITE]) to detect wider components. When combining all four SFRs, the short-period binary frequency is indistinguishable from that found by Duquennoy & Mayor ([CITE]) for the solar-type field stars which is also consistent with the previous result obtained by Mathieu ([CITE], [CITE]). When Oph-Sco is analyzed separately, it seems that there is an excess of short-period binaries of a factor 2–2.5. On the contrary, short-period binary systems seem to be absent in the sample containing stars in Cha/Lup/CrA. Such a trend was equally found by Mathieu ([CITE]) in Taurus. An excess of spectroscopic systems among the components of visual multiple systems is also observed.