Observations were made for a number of carbon-rich circumstellar envelopes using the Phoenix spectrograph on the Gemini South telescope to determine the abundance of small carbon chain molecules. Vibration-rotation lines of the ν3 antisymmetric stretch of C3 near 2040 cm−1 (4.902 μm) have been used to determine the column density for four carbon-rich circumstellar envelopes: CRL 865, CRL 1922, CRL 2023 and IRC +10216. We additionally calculate the column density of C5 for IRC +10216, and provide an upper limit for 5 more objects. An upper limit estimate for the C7 column density is also provided for IRC+10216. A comparison of these column densities suggest a revision to current circumstellar chemical models may be needed.
@article{arxiv.1408.5021,
title = {Small carbon chains in circumstellar envelopes},
author = {R. J. Hargreaves and K. Hinkle and P. F. Bernath},
journal= {arXiv preprint arXiv:1408.5021},
year = {2015}
}