Biases in the determination of dynamical parameters of star clusters: today and in the gaia era

Sollima, A., Baumgardt, H., Zocchi, A., Balbinot, E., Gieles, M., Henault-Brunet, V. and Varri, A. L. (2015) Biases in the determination of dynamical parameters of star clusters: today and in the gaia era. Monthly Notices of the Royal Astronomical Society, 451 2: 2185-2197. doi:10.1093/mnras/stv1079

Author Sollima, A.
Baumgardt, H.
Zocchi, A.
Balbinot, E.
Gieles, M.
Henault-Brunet, V.
Varri, A. L.
Title Biases in the determination of dynamical parameters of star clusters: today and in the gaia era
Journal name Monthly Notices of the Royal Astronomical Society   Check publisher's open access policy
ISSN 1365-2966
Publication date 2015-08-01
Sub-type Article (original research)
DOI 10.1093/mnras/stv1079
Open Access Status DOI
Volume 451
Issue 2
Start page 2185
End page 2197
Total pages 13
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Language eng
Formatted abstract
The structural and dynamical properties of star clusters are generally derived by means of the comparison between steady-state analytic models and the available observables. With the aim of studying the biases of this approach, we fitted different analytic models to simulated observations obtained from a suite of direct N-body simulations of star clusters in different stages of their evolution and under different levels of tidal stress to derive mass, mass function and degree of anisotropy. We find that masses can be under/overestimated up to 50 per cent depending on the degree of relaxation reached by the cluster, the available range of observed masses and distances of radial velocity measures from the cluster centre and the strength of the tidal field. The mass function slope appears to be better constrainable and less sensitive to model inadequacies unless strongly dynamically evolved clusters and a non-optimal location of the measured luminosity function are considered. The degree and the characteristics of the anisotropy developed in the N-body simulations are not adequately reproduced by popular analytic models and can be detected only if accurate proper motions are available. We show how to reduce the uncertainties in the mass, mass function and anisotropy estimation and provide predictions for the improvements expected when Gaia proper motions will be available in the near future.
Keyword Globular clusters: general
Methods: numerical
Methods: statistical
Stars: kinematics and dynamics
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2016 Collection
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Citation counts: TR Web of Science Citation Count  Cited 15 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 11 times in Scopus Article | Citations
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