@article{1538-4357-691-1-L55,
  author={Nimesh A. Patel and Ken H. Young and Sandra Brünken and Karl M. Menten and Patrick Thaddeus and Robert W. Wilson},
  title={Detection of Vibrationally Excited CO in IRC+10216},
  journal={The Astrophysical Journal Letters},
  volume={691},
  number={1},
  pages={L55},
  url={http://stacks.iop.org/1538-4357/691/i=1/a=L55},
  year={2009},
  abstract={Using the Submillimeter Array we have detected the J = 3-2 and 2-1 rotational transitions from within the first vibrationally excited state of CO toward the extreme carbon star IRC+10216 (CW Leo). The emission remains spatially unresolved with an angular resolution of ~2'' and, given that the lines originate from energy levels that are ~3100 K above the ground state, almost certainly originates from a much smaller (~10 14 cm) sized region close to the stellar photosphere. Thermal excitation of the lines requires a gas density of ~10 9 cm –3 , about an order of magnitude higher than the expected gas density based on previous infrared observations and models of the inner dust shell of IRC+10216.}
}