Searching for gas-rich disks around T Tauri stars in Lupus

Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands e-mail: kempen@strw.leidenuniv.nl

Received: 9 March 2006
Accepted: 7 June 2006

Abstract

Aims.We characterize the molecular environment of classical T Tauri stars in Lupus observed with the Spitzer Space Telescope in our search for gas-rich disks toward these sources.

Methods.Submillimeter observations of ¹²CO, ¹³CO, and C¹⁸O in the –2 and 2–1 lines were obtained with the James Clerk Maxwell Telescope toward a sample of 21 T Tauri stars with disks in the Lupus molecular clouds. Pointings at the sources and at selected off-positions are presented in order to disentangle material associated with disks from ambient cloud material.

Results.One source, IM Lup (Sz 82), was found with the double-peaked ¹²CO and ¹³CO profiles characteristic of a large rotating gas disk. The inclination of the disk is found to be ~, with an outer radius of 400–700 AU. For most other sources, including GQ Lup with its substellar companion, the single-dish ¹²CO lines are dominated by extended cloud emission with a complex velocity structure. No evidence of molecular outflows is found. Due to dense circumstellar material, compact C¹⁸O emission was detected toward only two sources. Future searches for gas-rich disks in Lupus should either use interferometers or perform very deep single-dish integrations in dense gas tracers to separate the cloud and disk emission.