Geology and Tectonics of Northwestern South America

Abstract

Two consecutive rotational transitions of the long cyanopolyyne HC 11 N, J 39 3 38 and 38 3 37, have been detected in the cold dust cloud TMC-1 at the frequencies expected from recent laboratory measurements by Travers and coworkers, and at about the expected intensities. The astronomical lines have a mean radial velocity of 5.8(1) km s 1 , in good agreement with the shorter cyanopolyynes HC 7 N and HC 9 N observed in this very sharp line source [5.82(5) and 5.84(5) km s 1 , respectively]. The column density of HC 11 N is calculated to be 2.8 10 11 cm 2. The abundance of the cyanopolyynes decreases smoothly with length to HC 11 N, the decrement from one to the next being about six for the longer carbon chains.