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A Keplerian disk around DM Tau ?

S.Guilloteau and A.Dutrey
Institut de Radio Astronomie Millimétrique, 300 Rue de la Piscine, F-38406 Saint Martin d'Hères
Abstract: Using the IRAM 30-m telescope, we have detected a rotating gas disk around the relatively old (5 10 yr) T Tauri star DM Tau. The kinematic pattern and line profiles obtained from CO J=2--1 and CO J=2--1 are consistent with a disk inclined about from face-on, with a rotation axis at PA , and orbiting a central star with a systemic velocity of . All detected lines can be well fitted by a simple Keplerian disk model with outer radius AU, mean temperature about 15 K, and standard isotopic ratios. If the CO abundance is normal, the total disk mass is .

Such a mass is small compared to that derived from mm and sub-mm continuum emission (). This can be explained either by CO depletion, or by an anomalous gas-to-dust ratio, or by the existence of a dense, compact, optically thick core which dominates the mm continuum emission. The size derived for such a core is consistent with the size of the current solar system. In all cases, our results indicate that significant amount of gas still exists several Myr after star formation.

Robert Lucas
Thu Mar 9 12:58:13 MET 1995