Star-forming gas in young clusters

Abstract

Initial conditions for star formation in clusters are estimated for protostars whose masses follow the initial mass function (IMF) from 0.05 to 10 solar masses. Star-forming infall is assumed equally likely to stop at any moment, due to gas dispersal dominated by stellar feedback. For spherical infall, the typical initial condensation must have a steep density gradient, as in low-mass cores, surrounded by a shallower gradient, as in the clumps around cores. These properties match observed column densities in cluster-forming regions when the mean infall stopping time is 0.05 Myr and the accretion efficiency is 0.5. The infall duration increases with final protostar mass, from 0.01 to 0.3 Myr, and the mass accretion rate increases from 3 to 300 x 10^(-6) solar masses/yr. The typical spherical accretion luminosity is ~5 solar luminosities, reducing the luminosity problem to a factor ~3. The initial condensation density gradient changes from steep to shallow at radius 0.04 pc, enclosing 0.9 solar masses, with mean column density 2 x 10^(22) cm^(-2), and with effective central temperature 16 K. These initial conditions are denser and warmer than those for isolated star formation.

To appear in Astrophysical Journal, May 2010

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• The Protostellar Luminosity Function
• The Luminosities of Protostars in the Spitzer c2d and Gould Belt Legacy Clouds
• Mass and Magnetic distributions in Self Gravitating Super Alfvenic Turbulence with AMR
• Filamentary condensations in a young cluster
• Star formation in dense clusters
• Mass and luminosity evolution of young stellar objects
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• Origin of the dense core mass function in contracting filaments
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• The Milky Way Atlas for Linear Filaments
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• Catalogue of High Protostellar Surface Density Regions in Nearby Embedded Clusters