Statistics of Multiple Star Systems Raphael Steinitz Netzach

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

Introduction Leading to multiple stellar systems - Dissolution of cluster - Capture

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.

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

Number of systems against multiplicity

Ln(Number of systems) against multiplicity

Misleading Data HD 319 319 319 Mag 5. 9 5. 9 Sp. T A 1 V A 3 V A 2 Vp A 1 V

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

Number of systems against multiplicity N(n)=5*106 e -2. 9 n

Ln(Number of systems) against multiplicity Ln(N)=-2. 847 n + 15. 5

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.