Star formation at 2 kpc and beyond: Sucesses and limitations of Spitzer
Harvard-Smithsonian Center for Astrophysics, Cambridge, USA
Imaging surveys of star-forming regions in the nearby molecular clouds
with the Spitzer Space Telescope (e.g. c2d, Taurus, Gould's Belt
Legacy projects) are complete to very low luminosities
and masses (well into the brown dwarf regime). From these surveys we
can draw inferences about the timescales for pre-main sequence evolution,
the efficience of star formation, and the structure of young clusters.
The situation is quite different for more distant, massive star forming regions at 2 kpc and beyond, where most stars form. The Spitzer observations of these regions are more biased and less sensitive than the nearby cloud surveys. I will discuss recent results for both nearby and more distant regions, and consider the limitations of the Spitzer data at 2 kpc and beyond, as well as prospects for improvement in the future.