SCYON Abstract

Received on December 2 2008

A New Diagnostic Method for Assessment of Stellar Stratification in Star Clusters

Authors	Dimitrios A. Gouliermis (¹), Richard de Grijs (²), and Yu Xin (²)
Affiliation	(¹) Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg, Germany (²) Department of Physics & Astronomy, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH, UK
Accepted by	Astrophysical Journal
Contact	dgoulier@mpia.de
URL	http://lanl.arxiv.org/abs/0811.4035
Links	Kron 1 / Lindsay 91

Abstract

We propose a new method for the characterization of stellar stratification in stellar systems. The method uses the mean-square radius (also called the Spitzer radius) of the system as a diagnostic tool. An estimate of the observable counterpart of this radius for stars of different magnitude ranges is used as the effective radius of each stellar species in a star cluster. We explore the dependence of these radii on magnitude as a possible indication of stellar stratification. This method is the first of its kind to use a dynamically stable radius, and though seemingly trivial it has never been applied before. We test the proposed method using model star clusters, which are constructed to be segregated on the basis of a Monte Carlo technique, and on Hubble Space Telescope observations of mass-segregated star clusters in order to explore the limitations of the method in relation to actual data. We conclude that the method performs efficiently in the detection of stellar stratification and its results do not depend on the data, provided that incompleteness has been accurately measured and the contamination by the field population has been thoroughly removed. Our diagnosis method is also independent of any model or theoretical prediction, in contrast to the `classical' methods used so far for the detection of mass segregation.