1. Statistics of Multiple Star Systems
Raphael Steinitz
Netzach Farbiash
Amir Hirsh
Lior Yosub
Physics Department, Ben-Gurion University
Beer-Sheva, Israel

2. Introduction Leading to multiple stellar systems
Dissolution of cluster
Capture

3. Capture probability independent of current multiplicity
Model
Capture probability independent of current multiplicity
N(n+1)=N(n)q
N(n+1)~qn~Ae-bn
A,b – constants depending on formation conditions of the multiple system.

4. The Data
Data taken from: The Catalogue of Stellar Projected Rotational Velocities;
Glebocki R., Gnacinski P., Stawikowski A., Acta Astron., 50, 509, 2000.
Multiplicity
Number of Systems 1
4691 2
1914 3
583 4
171 5 72 6 32 7 17 8 10 9

5. Number of systems against multiplicity

6. Ln(Number of systems) against multiplicity

7. Misleading Data HD
Mag
Sp.T
319
5.9
A1V
A3V
A2Vp

8. Number of verified systems
The Data
Multiplicity (n)
Number of systems (N)
Ln(N)
Number of verified systems 2
14110
9.55
14032 (0.6%) 3
1442
7.27
1439 (0.2%) 4 45
3.78
44 (2.2%)
Data taken from: The Washington Double Star Catalog;
Brian D. Mason, Gary L. Wycoff, and William I. Hartkopf, 2006

9. Number of systems against multiplicity
N(n)=5*106 e -2.9n

10. Ln(Number of systems) against multiplicity
Ln(N)=-2.847n

11. Final Remarks Capture mode can account (so far) the statistics.
It may not be the only mechanism leading to the observed statistics.
The current statistics pertain only to binaries, triples and quartets.
Future work should also address differences between spectral type classes.