EDP Sciences
Free access
Issue
A&A
Volume 411, Number 2, November IV 2003
Page(s) 91 - 97
Section Stellar clusters and associations
DOI http://dx.doi.org/10.1051/0004-6361:20034219


A&A 411, 91-97 (2003)
DOI: 10.1051/0004-6361:20034219

Research Note

How do binary separations depend on cloud initial conditions?

M. F. Sterzik1, R. H. Durisen2 and H. Zinnecker3

1  European Southern Observatory, Casilla 19001, Santiago 19, Chile
2  Department of Astronomy, SW319, Indiana University, Bloomington, Indiana 47405, USA
3  Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany



(Received 20 August 2003 / Accepted 28 August 2003 )

Abstract
We explore the consequences of a star formation scenario in which the isothermal collapse of a rotating, star-forming core is followed by prompt fragmentation into a cluster containing a small number ( $N \la 10$) of protostars and/or substellar objects. The subsequent evolution of the cluster is assumed to be dominated by dynamical interactions among cluster members, and this establishes the final properties of the binary and multiple systems. The characteristic scale of the fragmenting core is determined by the cloud initial conditions (such as temperature, angular momentum and mass), and we are able to relate the separation distributions of the final binary population to the properties of the star-forming core. Because the fragmentation scale immediately after the isothermal collapse is typically a factor of 3-10 too large, we conjecture that fragmentation into small clusters followed by dynamical evolution is required to account for the observed binary separation distributions. Differences in the environmental properties of the cores are expected to imprint differences on the characteristic dimensions of the binary systems they form. Recent observations of hierarchical systems, differences in binary characteristics among star forming regions and systematic variations in binary properties with primary mass can be interpreted in the context of this scenario.


Key words: stars: binaries: general -- stars: binaries: close -- stars: binaries: visual -- stars: formation -- stars: low-mass, brown dwarfs

Offprint request: M. Sterzik, msterzik@eso.org




© ESO 2003

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access.

An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account.
    In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.