The Monoceros R2 cloud - Near-infrared and molecular observations of a rotating collapsing cloud

Abstract

view Abstract Citations (88) References (44) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Monoceros R2 cloud: near-infrared and molecular observations of a rotating collapsing cloud. Loren, R. B. Abstract The velocity structure of the CO line profiles of the Mon R2 molecular cloud is studied for the combined effects of rotation and collapse motions. The CO line broadening shows that the collapse velocity (km s-1) is related to radial distance (pc) by V(r) - 4. 7r -112, if one assumes pure collapse, i.e., no turbulence. The numerical constant is in reality much less since turbulence probably makes a substantial contribution. The cloud rotates about a NW-SE axis with a projected angular velocity of 0.4 km 1 pc - . The rotation is a minor effect compared to the collapse. Free-fall collapse, along the rotational axis, can be observed as spatially extended high-velocity CO emission on the SE side and low-velocity emission on the opposite NW side of the dense core of the cloud. The comparison of the self-reversed CO and 13CO line profiles allows the sense of the large velocity gradient flow to be determined. This shows that the cloud is collapsing, not expanding. A comparison of CO, 6 cm and 2 mm H2CO, and recombination line profiles also shows that a self-consistent collapse model can be constructed with one continuum source, a compact H ii region, located on the far side of the dense molecular cloud. A second larger H ii region may lie in front of the dense core. A survey of the cloud at 2 m detected five sources; two sources located near the dense molecular core, including the brightest, have large infrared color indices, indicating Av 40 mag toward the center of the cloud. The dense nature of the core is confirmed by detection of the 3 m ice feature with TICE 1, toward the brightest infrared source. A comparison of the Av toward all the infrared sources, with the CO column densities, indicates that only 12Th of the carbon is found in CO molecules. Subject headings: infrared: sources - interstellar: molecules - nebulae: abundances - nebulae: general Publication: The Astrophysical Journal Pub Date: July 1977 DOI: 10.1086/155340 Bibcode: 1977ApJ...215..129L Keywords: Carbon Monoxide; Infrared Astronomy; Interstellar Matter; Molecular Spectra; Nebulae; Abundance; Formaldehyde; Gravitational Collapse; Hydroxyl Radicals; Line Spectra; Near Infrared Radiation; Spectral Line Width; Astrophysics full text sources ADS | data products SIMBAD (2)