Carbon monoxide observations of a rotating dust globule
Results are presented for observations of the J = 1-0 rotational lines of (C-12)(O-16), (C-13)(O-16), and (C-12)(O-18) at rest frequencies of 115.2712, 110.2014, and 109.7822 GHz, respectively, in the direction of the small dust cloud B361. For a distance of 350 pc, the cloud is found to have an overall radius of about 1.2 pc and a core radius of about 0.4 pc. The core density is estimated to be about 10,000 per cu cm, and it is shown that the density at the center is high enough for the CO to be collisionally thermalized. A cloud temperature of 8.5 K is determined, a lower limit of 125 solar masses is placed on the core mass, and it is suggested that most of the mass is contained within the inner 6% of the cloud volume. The dense inner core is found to be rotating with a velocity gradient of 2.9 km/s per pc. A n(CO)/n(H) ratio that is no more than 0.07 of the solar n(C)/n(H) ratio is derived, indicating that most of the carbon present in the cloud is not in the form of CO.