EPoS Contribution
EPoS Contribution
Linking the formation of molecular clouds and high-mass stars: the W43 case study

Frederique Motte
AIM Paris-Saclay CEA/IRFU - CNRS/INSU - Universite Paris Diderot, Gif-sur-Yvette, France
W43-Main is a prototypical Galactic mini-starburst region, i.e. a miniature model of starburst galaxies (Motte et al. 2003). I will review the first results of our "W43 consortium" in investigating the molecular complex inside which W43-Main has formed, in fine aiming to trace back the physical processes that have created such a high star formation activity over such a dense ~20 pc^2 cloud. We use a large observational database covering 100 pc to subparcsec scales and tracing atomic and molecular gases (HI, CO, N2H+... lines, Herschel, LABOCA continuum), star formation activity (Spitzer, Herschel) and we started using observational constraints to challenge numerical simulations of molecular cloud formation through converging flows. I will first show that, despite its large diameter and velocity dispersion (140 pc and 22 km/s), the newly-defined W43 molecular complex is close to Virial equilibrium with its densest parts most probably collapsing (Nguyen-Luong, Motte et al. 2011). The concentration of cloud material at high density (12% of the 7 10^6 Msun molecular cloud resides in <5 pc dust clumps) and the star formation rate of W43 (SFR up to 0.1 Msun/yr) are very high when compared to molecular clouds known in the Milky Way. These extreme characteristics are consistent with the location of W43 at the tip of the long bar of the Milky Way. I will then present the first hints we collected arguing for the formation of this extreme molecular complex by colliding flows: tight connection of CO and HI gases, global collapse of the W43-Main cloud, velocity shears and shocks where filaments merge towards the densest parts of W43 (called ridges)...
Q. Nguyen-Luong, CITA, Canada
P. Schilke, U-Koeln, Germany
F. Heitsch, U-North Carolina Chapel Hill, USA
S. Bontemps, LAAB, France
N. Schneider, LAAB, France
The W43 IRAM Large Program consortium.
Key publication