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Published online by Cambridge University Press: 04 August 2017
The latitude distribution of the emission from the 12CO J=1→0 rotational transition has been surveyed for the region 350° ≤ 1 ≤ 25° at b = 0′, ±10′ and ±20′. Most of the 12CO emission in the inner Galaxy, the region extending from the galactic center to 4 kpc radius, is produced by three large and massive objects: the nuclear disk/bar, the 3-kpc arm and the “+135 km s-1 feature”. These structures all have observed HI counterparts and each shows extremely large deviations (50–180 km s-1) from circular motion. Observations of 13CO in selected directions show that the two structures outside the nuclear disk each span at least 2 kpc in length and that together they imply ≥ 1055 ergs in kinetic energy of expansion away from the galactic nucleus.