VIBRATIONALLY EXCITED HCN AROUND AFGL 2591: A PROBE OF PROTOSTELLAR STRUCTURE

作者：Veach Todd J^*; Groppi Christopher E; Hedden Abigail

来源：Astrophysical Journal Letters, 2013, 765(2): L34.

DOI：10.1088/2041-8205/765/2/L34

• ISM: molecules
• stars: formation
• stars: individual (AFGL 2591)
• stars: kinematics and dynamics
• stars: protostars
• submillimeter: stars

Vibrationally excited molecules with submillimeter rotational transitions are potentially excellent probes of physical conditions near protostars. This study uses observations of the upsilon = 1 and upsilon = 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 and follow-up observations from the Submillimeter Array. All vibrationally excited HCN (4-3) upsilon = 0, upsilon = 1, and upsilon = 2 lines were observed. The existence of the three upsilon = 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 upsilon = 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.

• 出版日期2013-3-10