Patel, Nimesh A.Young, Ken H.Bruenken, SandraMenten, Karl M.Thaddeus, PatrickWilson, Robert W.2010-11-302010-11-302010-11-30200910.1088/0004-637X/691/1/L55https://infoscience.epfl.ch/handle/20.500.14299/60504WOS:000263148600013Using 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.circumstellar matterradio lines: starsstars: individual (IRC+10216)stars: late-typesubmillimeterLate-Type StarsMaser EmissionSio MasersIrc &10216ExcitationEnvelopeGhzC4Htext::journal::journal article::research article