C.D.S. - SIMBAD4 rel 1.7 - 2020.01.28CET10:39:55

2013A&A...549A.132P - Astronomy and Astrophysics, volume 549A, 132-132 (2013/1-1)

Local-density-driven clustered star formation.


Abstract (from CDS):

A positive power-law trend between the local surface densities of molecular gas, Σgas, and young stellar objects, Σ*, in molecular clouds of the solar neighbourhood has recently been identified. How it relates to the properties of embedded clusters, in particular to the recently established radius-density relation, has so far not been investigated. We model the development of the stellar component of molecular clumps as a function of time and initial local volume density. Our study provides a coherent framework able to explain both the molecular-cloud and embedded-cluster relations quoted above. We associate the observed volume density gradient of molecular clumps to a density-dependent free-fall time. The molecular clump star formation history is obtained by applying a constant star formation efficiency per free-fall time, εff. For the volume density profiles typical of observed molecular clumps (i.e. power-law slope ≃-1.7), our model gives a star-gas surface-density relation of the form Σ*∝Σgas2, which agrees very well with the observations. Taking the case of a molecular clump of mass M0≃104M and radius R≃6pc experiencing star formation during 2Myr, we derive what star formation efficiency per free-fall time matches the normalizations of the observed and predicted (Σ*, Σgas) relations best. We find εff≃0.1. We show that the observed growth of embedded clusters, embodied by their radius-density relation, corresponds to a surface density threshold being applied to developing star-forming regions. The consequences of our model in terms of cluster survivability after residual star-forming gas expulsion are that, owing to the locally high star formation efficiency in the inner part of star-forming regions, global star formation efficiency as low as 10% can lead to the formation of bound gas-free star clusters.

Abstract Copyright:

Journal keyword(s): stars: formation - galaxies: star clusters: general - ISM: clouds - stars: kinematics and dynamics

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
1 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 1924 1
2 NAME Trapezium Cluster As* 05 35 16.5 -05 23 14           ~ 1441 1
3 NAME Mon R2 HII 06 07 46.6 -06 22 59           ~ 640 2
4 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 2964 0
5 Cl Westerlund 1 OpC 16 47 04.00 -45 51 04.9           ~ 449 0
6 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11184 0

    Equat.    Gal    SGal    Ecl

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