Astron. Astrophys. 338, L63-L66 (1998)

1. Introduction

Observations of young stars in the sub-mm and mm-wavelength continuum provide strong evidence for the theoretical expectation that they are surrounded by evolving, circumstellar disks (e.g. Beckwith et al. 1990, B90). However, only angularly resolved kinematic data can discriminate among, for example, rotating disks, infalling material, and outflows. Since young stars are usually in or near molecular cloud material with various velocity components, it has proven difficult to obtain data whose interpretation is unambiguous.

GM Aur is a single, classic T Tauri (cTT) star located at pc distance at the edge of the CO emission associated with L 1517 (Herbig & Bell 1988; Elias 1978). With an estimated age of to y, GM Aur is relatively old compared to other stars in Taurus-Auriga (B90, Simon & Prato 1995). Koerner et al. (1993, K93) detected the molecular emission of the cold outer circumstellar disk by interferometry of the   line. These and subsequent interferometric observations at resolution, and Hubble Space Telescope images show a flared disk in rotation at inclination and position angle (Koerner 1997, Stapelfeldt et al. 1995). The upgrade of the IRAM interferometer to dual-frequency receivers (2.7 and 1.3 mm) and an extension of the baselines now provides resolution below 1-1.5". We therefore began a new series of observations to improve our understanding of the circumstellar material around GM Aur.

© European Southern Observatory (ESO) 1998

Online publication: September 14, 1998
helpdesk@link.springer.de