Variations in the HCN/HNC abundance ratio in the Orion molecular cloud.

We have used observations of the rare isotopes of HCN and HNC to determine the relative abundance of these two chemical isomers along the central ridge of the Orion molecular cloud. The abundance ratio [HCN]/[HNC] decreases by more than an order of magnitude from the relatively warm plateau and hot core sources toward the KL nebula to the colder, more quiescent clouds to the north and south. Even in the cooler regions, however, the ratio is an order of magnitude larger than that found in previous investigations of cold dark clouds.

The spectra of Orion A and IRC + 10216 between 72.2 and 91.1 GHz.

The complete spectra of Orion A and IRC +10216 in the range 72.2 to 91.1 GHz, obtained with the 20 m mm-wave telescope at the Onsala Space Observatory, are presented.

Spectral scan of Orion A and IRC+10216 from 72 to 91 GHz.

The spectra of the Orion KL molecular cloud and the envelope of the carbon star IRC+10216 have been surveyed at 1 MHz resolution over the interval 72.2-91.1 GHz to a sensitivity (in terms of main beam brightness temperature) usually better than 0.