Issue |
A&A
Volume 384, Number 3, March IV 2002
|
|
---|---|---|
Page(s) | 1030 - 1037 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20020105 | |
Published online | 15 March 2002 |
Relative orientation of orbits in triple stars *
1
European Southern Observatory, Casilla 19001, Santiago 19, Chile
2
Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile
Corresponding author: M. Sterzik, msterzik@eso.org
Received:
6
December
2001
Accepted:
15
January
2002
Statistical analysis of the relative alignment of inner
and outer orbits in triple systems resulting from a dynamical
decay of small-N clusters () is presented and
compared to the statistics of real multiple stars. The
distribution of the relative angle Φ between the angular
momentum vectors of inner and outer orbits in triple stars
formed by decay is shown to depend on the initial cluster
conditions like geometry, mass function, rotational and thermal
energy. For a realistic set of initial conditions, a modest
alignment of orbital momentum vectors is found, in good
agreement with the latest observational data on visual multiple
stars exhibiting an average
between
and
. The relation between eccentricities of
outer orbits and period ratios for both simulated and real
triples is consistent with a slightly adjusted formulation of the
stability criterium by Mardling & Aarseth (2001). Dynamical decay
can therefore explain the weak correlation of orbital orientations
observed in multiple stars. Using modern high-resolution
techniques, the observed statistics of Φ should be extended
as it will allow one to sensitively constrain properties of initial
clusters.
Key words: stars: binaries: general / visual / stars: formation / stellar dynamics
© ESO, 2002
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