Early stages of clustered star formation throughout the Galaxy

by Wilfred Frieswijk (Kapteyn Astronomical Institute)

Friday 24 Oct 2008, 10:30 → 12:00 Europe/Stockholm

FA31

Cluster-forming clumps are the densest condensations inside Giant Molecular Clouds and represent the youngest stage of star-cluster formation. Massive stars form almost exclusively in such clustered environments, where supposedly the majority of all stars in the Galaxy form. In the absence of bright mid-IR emission toward most of the outer Galactic plane, and because large scale (sub-) mm surveys are not available yet, the majority of cluster-forming clumps has been identified toward the inner parts of the Galaxy as infrared dark clouds (IRDCs). I will present a recent investigation of the near-IR color distribution of stars in 2MASS, based on a statistical measurement of reddening, that resulted in a catalog including ‘cluster-forming-clump’-candidates toward the outer Galactic plane. These ‘cluster-forming-clump’-candidates show high reddening and match with CO emission at discrete velocities, verifying the presence of molecular clouds. I will show recent results of molecular line- and Spitzer observations that led to the identification of the first IRDC toward the outer Galaxy. The identification of cluster-forming clumps at large Galacto-centric radius opens up opportunities to investigate the early stages of clustered star formation in quiescent regions of the Galaxy. That is, where external conditions are different compared to the turmoil toward the inner Galaxy. (Host: Garrelt Mellema)