Abstract
Vibrationally excited molecules with submillimeter 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 and follow-up observations from the Submillimeter Array. 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 (1010 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.
Original language | English (US) |
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Article number | L34 |
Journal | Astrophysical Journal Letters |
Volume | 765 |
Issue number | 2 |
DOIs | |
State | Published - Mar 10 2013 |
Keywords
- ISM: molecules
- stars: formation
- stars: individual (AFGL 2591)
- stars: kinematics and dynamics
- stars: protostars
- submillimeter: stars
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science