NGC 2264 molecular cloud: Ammonia and OH observations

Line emission from OH and HN3 has been mapped in the region of the young star cluster NGC 2264. The NH3 emission has been resolved into two components which are joined by a major axis lying along the galactic plane. A systematic velocity gradient of 3 km s-1 has been measured across the 2 pc extent of the NH3 emission, and this gradient is interpreted in terms of a ''rotation'' of the two components about a minor axis centered midway between them and inclined at 900 to the galactic plane. The inferred rotation period of 4 million years corresponds to a Keplerian mass of approx.103 M/sub sun/. The NH3 emission suggests an embryonic binary star system whose angular momentum could have been derived from the gravitational collapse of a differentially rotating interstellar cloud with a size of approx.10 pc, a molecular hydrogen number density of approx.5 cm-3, a temperature of approx.10 K, and a Jeans mass of approx.103 M/sub sun/. Because the OH emission is excited in the more tenuous parts of the region, it is more extensive and has a center shifted away from one of the NH3 components in a direction where shearing motions may exist