Introduction And Observations

The formation of low mass stars and planetary systems is one of the most interesting astronomical themes, because it is very closely related to the origin of the Solar System. Observationally, extensive flux surveys at mm and sub-mm wavelengths were performed by Beckworth et al. [1] and Osterloh and Beckwith [2]. They revealed that more than a half of young stellar objects (YSOs) in the Taurus Molecular Cloud (TMC) are accompanied with considerable millimeter excess emission. The excess can be explained well by the thermal emission from the compact dust disk whose radii are a few x 100 AU and masses are a few x 0.01 M® [1,3,2],

To investigate the disk properties more accurately, we have observed 141 GHz dust emission around 3 YSOs with the NMA from December 1998 to February 1999. The target sources are HL Tau, DO Tau, and GM Aur, which have strong continuum emission. HL Tau is now categorized as a protostar, whose stellar age is estimated to be 1 X 105

'Present address: Nobeyama Radio Observatory, Nobeyama, Minamimaki, Minamisaku, Nagano, 3841305, Japan yr. DO Tau and GM Aur are categorized as classical T Tauri star and their stellar ages are estimated to be 6 x 105 yr for DO Tau, and 2 x 106 yr for GM Aur [1,4].

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