2014AJ....147...46Z

We present observations of a 4.25 deg² area toward the North American and Pelican Nebulae in the J = 1-0 transitions of ¹²CO, ¹³CO, and C¹⁸O. Three molecules show different emission areas with their own distinct structures. These different density tracers reveal several dense clouds with a surface density of over 500 M_☉pc^–2 and a mean H₂ column density of 5.8, 3.4, and 11.9x10²¹/cm2 for ¹²CO, ¹³CO, and C¹⁸O, respectively. We obtain a total mass of 5.4x10⁴ M_☉(¹²CO), 2.0x10⁴ M_☉(¹³CO), and 6.1x10³ M_☉(C¹⁸O) in the complex. The distribution of excitation temperature shows two phases of gas: cold gas (∼10 K) spreads across the whole cloud; warm gas (>20 K) outlines the edge of the cloud heated by the W80 H II region. The kinetic structure of the cloud indicates an expanding shell surrounding the ionized gas produced by the H II region. There are six discernible regions in the cloud: the Gulf of Mexico, Caribbean Islands and Sea, and Pelican's Beak, Hat, and Neck. The areas of ¹³CO emission range within 2-10 pc² with mass of (1-5)x10³ M_☉ and line width of a few km/s. The different line properties and signs of star-forming activity indicate they are in different evolutionary stages. Four filamentary structures with complicated velocity features are detected along the dark lane in LDN 935. Furthermore, a total of 611 molecular clumps within the ¹³CO tracing cloud are identified using the ClumpFind algorithm. The properties of the clumps suggest that most of the clumps are gravitationally bound and at an early stage of evolution with cold and dense molecular gas.