Detection Of Vibrationally Excited Co In Irc+10216

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 similar to 2 '' and, given that the lines originate from energy levels that are similar to 3100 K above the ground state, almost certainly originates from a much smaller (similar to 10(14) cm) sized region close to the stellar photosphere. Thermal excitation of the lines requires a gas density of similar to 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.