1998AJ....116..336N

We present the results of new ¹³CO J = 1-0 observations of the Orion A molecular cloud made with two 4 m telescopes at Nagoya University. The area observed, corresponding to l ∼ 208°-215° and b ∼ -20°.5 to -18°.0, covers the full extent of this giant molecular cloud at a 2'.0 grid spacing with a 2'.7 beam. The present observations provide the first complete coverage of the cloud in ¹³CO with a reasonably high angular resolution relative to the cloud's size. In addition, the high velocity resolution of 0.1 km.s^–1 allowed us to resolve velocity components of the ¹³CO emission. The molecular distribution is highly elongated along the Galactic plane and is filamentary, as is consistent with previous molecular maps. The total molecular mass of the cloud is estimated to be ∼5.4x10⁴ M_☉. By using the velocity channel maps every 0.5 km.s^–1, 39 individual filamentary components have been identified, and their basic physical quantities have been estimated. They typically are 4.8 pc in length, 1.4 pc in width, and 660 M_☉ in mass. We also find that these filamentary components are nearly in virial equilibrium.