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We have mapped the Orion-A giant molecular cloud in the CO(J=4-3) line with the Tsukuba 30cm submillimeter telescope. The map covered a 7.125 deg2 area with a 9' resolution, including main components of the cloud such as the Orion Nebula, OMC- 2/3, and L1641-N. The most intense emission was detected toward the Orion KL region. The integrated intensity ratio between CO(J=4-3) and CO(J=1-0) was derived using data from the Columbia-Universidad de Chile CO survey, which was carried out with a comparable angular resolution. The ratio was r4−3/1−0 ∼0.2 in the southern region of the cloud and 0.4-0.8 at star forming regions. We found a trend that the ratio shows higher values at the edges of the cloud. In particular, the ratio at the northeastern edge of the cloud at (l, b) ≈ (208. ° 375, −19. ° 0) shows the highest value of 1.1. The physical condition of the molecular gas in the cloud was estimated by non-LTE calculation. The result indicates that the kinetic temperature has a gradient from north (Tkin = 80 K) to south (20 K). The estimation shows that the gas associated with the edge of the cloud is warm (Tkin ∼60 K), dense (nH2 ∼ 104 cm−3), and optically thin, which may be explained by heating and sweeping of interstellar materials from OB clusters. [ABSTRACT FROM AUTHOR]

Spectral line surveys reveal rich molecular reservoirs in G331.512–0.103, a compact radio source in the center of an energetic molecular outflow. In this first work, we analyze the physical conditions of the source by means of CH3OH and CH3CN. The observations were performed with the APEX Telescope. Six different system configurations were defined to cover most of the band within (292–356) GHz; as a consequence, we detected a forest of lines toward the central core. A total of 70 lines of A/E–CH3OH and A/E–CH3CN were analyzed, including torsionally excited transitions of CH3OH (). In a search for all the isotopologues, we identified transitions of 13CH3OH. The physical conditions were derived considering collisional and radiative processes. We found common temperatures for each A and E symmetry of CH3OH and CH3CN; the derived column densities indicate an A/E equilibrated ratio for both tracers. The results reveal that CH3CN and CH3OH trace a hot and cold component with K and K, respectively. In agreement with previous ALMA observations, the models show that the emission region is compact () with gas density n(H2) = (0.7–1)×107 cm−3. The CH3OH/CH3CN abundance ratio and the evidences for prebiotic and complex organic molecules suggest a rich and active chemistry toward G331.512–0.103. [ABSTRACT FROM AUTHOR]