Abstract
We report the first detection of the 205 μm 3P1-->3P0 [N II] line from a ground-based observatory using a direct detection spectrometer. The line was detected from the Carina star formation region using the South Pole Imaging Fabry-Perot Interferometer (SPIFI) on the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) at the South Pole. The [N II] 205 μm line strength indicates a low-density (n~32 cm-3) ionized medium, similar to the low-density ionized halo previously reported in its [O III] 52 and 88 μm line emission. When compared with the Infrared Space Observatory [C II] observations of this region, we find that 27% of the [C II] line emission arises from this low-density ionized gas, but the large majority (~73%) of the observed [C II] line emission arises from the neutral interstellar medium. This result supports and underpins prior conclusions that most of the observed [C II] 158 μm line emission from Galactic and extragalactic sources arises from the warm, dense photodissociated surfaces of molecular clouds. The detection of the [N II] line demonstrates the utility of Antarctic sites for THz spectroscopy.
Original language | English |
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Pages (from-to) | L125-L128 |
Number of pages | 4 |
Journal | Astrophysical Journal. Letters |
Volume | 652 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2006 |
Externally published | Yes |
Keywords
- ISM: H II Regions; Infrared: ISM; Instrumentation: Spectrographs; ISM: Atoms; ISM: Individual: Name: Carina Nebula; ISM: Lines and Bands; Astrophysics