Circumstellar medium around close southern PMS binaries^*

New results with the ESO ADONIS + COMIC/SHARP infrared system

¹ Laboratoire d'Astrophysique, Observatoire de Grenoble, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex, France
² CNES, 18 Av. E. Belin, 31400 Toulouse, France e-mail: Herve.Geoffray@cnes.fr
³ Institut Universitaire de France

Corresponding author: J.-L. Monin, Jean-Louis.Monin@obs.ujf-grenoble.fr

Received: 12 December 2000
Accepted: 19 January 2001

Abstract

We have started a series of high angular resolution observations of close southern pre Main-Sequence (PMS) binary systems in order to study their respective photometry from 1 to 5 μm. For most of the binaries of our sample, we present the first near infrared (NIR) measurements longward of m on both components. From these measurements we characterize the stellar Spectral Energy Distribution (SED) of the primary and its companion, adjust standard photospheres to estimate their luminosities & temperatures, hence masses & ages through the use of an HR diagram. At the same time, we study the presence of circumstellar material around our PMS targets, in order to assess how the eventually leftover material is distributed after contraction. We find the same proportion of mixed systems (CTTS/WTTS) as in the overall southern clouds and all these mixed systems are found with mass ratios <0.5; all the WTTS/WTTS systems of our sample are found in binaries closer than 60 AU; apart from one of the most separated binaries, all our objects appear coeval.