Vibrationally excited molecules with sub-mm rotational transitions are potentially excellent probes of physical conditions near protostars .
This study uses observations of the v = 1 and v = 2 ro-vibrational modes of HCN ( 4-3 ) to probe this environment .
The presence or absence and relative strengths of these ro-vibrational lines probe the gas excitation mechanism and physical conditions in warm , dense material associated with protostellar disks .
We present pilot observations from the Heinrich Hertz Submillimeter Telescope ( HHSMT ) and followup observations from the Submillimeter Array ( SMA ) .
All vibrationally excited HCN ( 4-3 ) v = 0 , v = 1 , and v = 2 lines were observed .
The existence of the three v = 2 lines at approximately equal intensity imply collisional excitation with a density of greater than ( 10 ^ { 10 } cm ^ { -3 } ) and a temperature of > 1000 K for the emitting gas .
This warm , high density material should directly trace structures formed in the protostellar envelope and disk environment .
Further , the line shapes of the v = 2 emission may suggest a Keplerian disk .
This letter demonstrates the utility of this technique which is of particular interest due to the recent inauguration of the Atacama Large Millimeter Array ( ALMA ) .