Detection of the 205 um [NII] Line from the Carina Nebula

• Main Authors: Oberst, T. E., Parshley, S. C., Stacey, G. J., Nikola, T., Loehr, A., Harnett, J. I., Tothill, N. F. H., Lane, A. P., Stark, A. A., Tucker, C. E.
• Format: Text
• Language: unknown
• Published: arXiv 2006
• Subjects: Astrophysics astro-ph; FOS Physical sciences; Antarctic; The Antarctic; South Pole; Antarc*; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.astro-ph/0610636; https://arxiv.org/abs/astro-ph/0610636

We report the first detection of the 205 um 3P1 - 3P0 [NII] 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 South Pole. The [NII] 205 um line strength indicates a low-density (n ~ 32 cm^-3 ionized medium, similar to the low-density ionized halo reported previously in its [OIII] 52 and 88 um line emission. When compared with the ISO [CII] observations of this region, we find that ~27% of the [CII] line emission arises from this low-density ionized gas, but the large majority ~ 73% of the observed [CII] line emission arises from the neutral interstellar medium. This result supports and underpins prior conclusions that most of the observed [CII] 158 um line emission from Galactic and extragalactic sources arises from the warm, dense photodissociated surfaces of molecular clouds. The detection of the [NII] line demonstrates the utility of Antarctic sites for THz spectroscopy. : 8 pages, 2 figures. To appear in the Astrophysical Journal Letters