Do All Stars in the Solar Neighbourhood Form in Clusters?

Conference paper
First Online:
Part of the Astrophysics and Space Science Proceedings book series (ASSSP)

Abstract

We present a global study of low mass, young stellar object (YSO) surface densities (Σ) in nearby (<500 pc) star forming regions based on a comprehensive collection of Spitzer Space Telescope surveys. We show that the distribution of YSO surface densities is a smooth distribution, being adequately described by a lognormal function from a few to 103 YSOs per { pc}2, with a peak at ∼ 22 stars { pc}−2. The observed lognormal Σ is consistent with predictions of hierarchically structured star-formation at scales below 10pc, arising from the molecular cloud structures. We do not find evidence for multiple discrete modes of star-formation (e.g.clustered and distributed). Comparing the observed Σ distribution to previous Σ threshold definitions of clusters show that they are arbitrary. We find that only a low fraction (<26%) of stars are formed in dense environments where their formation/evolution (along with their circumstellar disks and/or planets) may be affected by the close proximity of their low-mass neighbours.

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Notes

Acknowledgements

We would like to thank the organisers of the JENAM Star Clusters in the Era of Large Surveys meeting for arranging the program and inviting us to contribute our work. Additionally, Eli Bressert’s trip to the meeting was possible due to the CONSTELLATION network and funds.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  1. 1.School of PhysicsUniversity of ExeterExeterUK
  2. 2.University of Massachusetts, Smith CollegeNorthamptonUSA

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