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Masson, C. R.

Publications and source records attributed to Masson, C. R..

HC3N maps of OMC1

We have made 3.8 sec resolution maps of HC3N (J = 12-11) and 2.7 mm continuum emission in OMC1 using the OVRO mm interferometer. The continuum map, which traces dust column density, shows that the hot core region consists of several clumps, the densest of which lies 3 sec SE of IRc2. HC3N, which traces dense gas, shows the velocity structure in the region. There is no simple pattern of rotation or expansion, nor does the emission resemble a disk centered on IRc2. Since the velocity difference between the hot core and IRc2 and the velocity dispersion in the hot core are comparable with the orbital velocity at a distance of 3 sec. from a 20 M(solar) object, it is possible that the hot core material is bound to IRc2. In the channel at 10.4 km s(-1) V(LSR), we detect strong emission from the source 20 sec NE of IRc2, which confirms indications from continuum and CS (J = 2-1) maps that this is a very dense, possibly protostellar, object. This emission is clearly resolved from the hot core and is elongated north-south, along the direction of the ridge emission. An additional interesting feature in these maps is a compact high velocity source located 4 sec SW of IRc2. This source has a velocity dispersion greather than 20 km/s (FWHM) and is spatially coincident with the zero-offset source seen by Pauls et al. (1983) and a point source in the near IR images taken by Allen et al. (1984). The large localized velocity, dispersion and the highly obscured IR source suggest that this compact source is an outflow from a young stellar companion to IRc2.

Masson, C. R.↗

Aperture-synthesis observations of carbon monoxide in the Egg Nebula

Observations of the 2.6-mm CO emission of the bipolar nebular CRL 2688, obtained with resolution 7 arcsec using the mm-wave interferometer at Owens Valley during December 1982-June 1983, are reported. The emission of a 10 x 15-arcsec core, centered on the optical reflection nebula and probably surrounded by a large cloud of cooler gas, is found to have a main-axis velocity gradient of 3 km/s arcsec and an excitation temperature of about 70 K.

Heiligman, G. M.↗

C-13H3OH in OMC-1

Transition line data for C-13H3OH in OMC-1 were gathered with a superconducting tunnel junction receiver and a 512 channel spectrometer on a 10.4 m telescope at the Owens Valley Radio Observatory. The methanol was scanned at 236 GHz and an observational efficiency of 85 percent. The survey was carried out to complement the data base on the line frequencies of internal rotors such as methanol and thereby the resolution of the C-12/C-13 ratio toward the galactic center. The data indicated that previous emission lines attributed to CO(+) and CH3CHO are actually methanol emissions, and the associated C-12/C-13 ratio is about 30.

Blake, G. A.↗