Two consecutive rotational transitions of the long cyanopolyyne HC11N, J=39-38, and J=38-37, have been detected in the cold dust cloud TMC-1 at the frequencies expected from recent laboratory measurements by Travers et al. (1996), and at about the expected intensities. The astronomical lines have a mean radial velocity of 5.8(1) km/s, in good agreement with the shorter cyanopolyynes HC7N and HC9N observed in this very sharp-lined source [5.82(5) and 5.83(5) km/s, respectively]. The column density of HC11N is calculated to be 2.8x10^(11) cm^(-2). The abundance of the cyanopolyynes decreases smoothly with length to HC11N, the decrement from one to the next being about 6 for the longer carbon chains.
@article{arxiv.astro-ph/9704233,
title = {Detection of HC11N in the Cold Dust Cloud TMC-1},
author = {M. B. Bell and P. A. Feldman and M. J. Travers and M. C. McCarthy and C. A. Gottlieb and P. Thaddeus},
journal= {arXiv preprint arXiv:astro-ph/9704233},
year = {2009}
}