Herschel far-infrared observations of the Carina Nebula complex. I. Introduction and global cloud structure

Abstract

Context. The Carina Nebula represents one of the most massive star forming regions known in our Galaxy and displays a high level of feedback from the large number of very massive stars. While the stellar content is now well known from recent deep X-ray and near-infrared surveys, the properties of the clouds remained rather poorly studied until today.
Aims: By mapping the Carina Nebula complex in the far-infrared, we aim at a comprehensive and detailed characterization of the dust and gas clouds in the complex.
Methods: We used SPIRE and PACS onboard of Herschel to map the full spatial extent (≈5.3 square-degrees) of the clouds in the Carina Nebula complex at wavelengths between 70 μm and 500 μm. We used here the 70 μm and 160 μm far-infrared maps to determine color temperatures and column densities, and to investigate the global properties of the gas and dust clouds in the complex.
Results: Our Herschel maps show the far-infrared morphology of the clouds at unprecedented high angular resolution. The clouds show a very complex and filamentary structure that is dominated by the radiation and wind feedback from the massive stars. In most locations, the column density of the clouds is N_H ≲ 2 × 10²² cm^-2 (corresponding to visual extinctions of A_V ≲ 10 mag); denser cloud structures are restricted to the massive cloud west of Tr 14 and the innermost parts of large pillars. Our temperature map shows a clear large-scale gradient from ≈35-40 K in the central region to ≲20 K at the periphery and in the densest parts of individual pillars. The total mass of the clouds seen by Herschel in the central (1 degree radius) region is ≈656 000 M_⊙. We also derive the global spectral energy distribution in the mid-infrared to mm wavelength range. A simple radiative transfer model suggests that the total mass of all the gas (including a warmer component that is not well traced by Herschel) in the central 1 degree radius region is ≤890 000 M_⊙.
Conclusions: Despite the strong feedback from numerous massive stars and the corresponding cloud dispersal processes that are going on since several million years, there are still several 10 000 M_⊙ of cool cloud material present at column-densities sufficient for further star formation. Comparison of our total gas mass estimates to molecular cloud masses derived from CO line mapping suggests that as much as about 75% of all the gas is in atomic rather than molecular form.

The Herschel data described in this paper have been obtained in the open time project OT1_tpreibis₁ (PI: T. Preibisch). Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendix A is available in electronic form at http://www.aanda.org