Volume 560, December 2013
|Number of page(s)||25|
|Section||Interstellar and circumstellar matter|
|Published online||29 November 2013|
1 1. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
2 Canadian Institute for Theoretical Astrophysics – CITA, University of Toronto, Toronto, Ontario, M5S 3H8, Canada
3 Laboratoire AIM, CEA/IRFU – CNRS/INSU – Université Paris Diderot, Service d’Astrophysique, Bât. 709, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
4 Univ. Bordeaux, LAB, UMR 5804, 33270 Floirac, France
5 CNRS, LAB, UMR 5804, 33270 Floirac, France
6 Max-Planck-Institut für Astronomie, Königsstuhl 17, 69117 Heidelberg, Germany
7 Department of Physics and Astonomy, University of North Carolina Chapel Hill, CB 3255, Phillips Hall, Chapel Hill, NC 27599, USA
8 Instituto Radioastronomía Milimétrica, Av. Divina Pastora 7, Nucleo Central, 18012 Granada, Spain
9 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
Received: 28 March 2013
Accepted: 29 August 2013
We aim to fully describe the distribution and location of dense molecular clouds in the giant molecular cloud complex W43. It was previously identified as one of the most massive star-forming regions in our Galaxy. To trace the moderately dense molecular clouds in the W43 region, we initiated W43-HERO, a large program using the IRAM 30 m telescope, which covers a wide dynamic range of scales from 0.3 to 140 pc. We obtained on-the-fly-maps in 13CO (2–1) and C18O (2–1) with a high spectral resolution of 0.1 km s-1 and a spatial resolution of 12′′. These maps cover an area of ~1.5 square degrees and include the two main clouds of W43 and the lower density gas surrounding them. A comparison to Galactic models and previous distance calculations confirms the location of W43 near the tangential point of the Scutum arm at approximately 6 kpc from the Sun. The resulting intensity cubes of the observed region are separated into subcubes, which are centered on single clouds and then analyzed in detail. The optical depth, excitation temperature, and H2 column density maps are derived out of the 13CO and C18O data. These results are then compared to those derived from Herschel dust maps. The mass of a typical cloud is several 104 M⊙ while the total mass in the dense molecular gas (>102 cm-3) in W43 is found to be ~1.9 × 106 M⊙. Probability distribution functions obtained from column density maps derived from molecular line data and Herschel imaging show a log-normal distribution for low column densities and a power-law tail for high densities. A flatter slope for the molecular line data probability distribution function may imply that those selectively show the gravitationally collapsing gas.
Key words: ISM: structure / ISM: kinematics and dynamics / ISM: molecules / molecular data / stars: formation
Appendices are available in electronic form at http://www.aanda.org
The final datacubes (13CO and C18O) for the entire survey are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/560/A24
© ESO, 2013
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