Internal rotation is considered to play a major role in determining the structure and dynamics of some globular clusters. We present a dynamical analysis of the photometry and three-dimensional kinematics of 47 Tuc and ω Cen, by means of a new family of self-consistent axisymmetric rotating models. The combined use of line-of-sight velocities and proper motions allows us to obtain a global description of the internal dynamical structure of the objects together with an estimate of their dynamical distances. The well-relaxed cluster 47 Tuc is very well interpreted by our dynamical models; in particular, internal rotation is found to explain the observed morphology. For the partially relaxed cluster ω Cen, the selected model provides a good representation of its complex three-dimensional kinematics, in general qualitative agreement with the observed anisotropy profile, which is characterized by tangential anisotropy in the outer parts; discrepancies are found between the observed and the expected ellipticity profile and are ascribed to the presence of a high degree of radial anisotropy in the intermediate region and to its interplay with rotation.

The flattening of globular clusters : internal rotation or velocity anisotropy? / P. Bianchini, A.L. Varri, G. Bertin, A. Zocchi. - In: MEMORIE DELLA SOCIETÀ ASTRONOMICA ITALIANA. - ISSN 1824-016X. - 84:1(2013), pp. 183-186. ((Intervento presentato al convegno Reading the book of globular clusters with the lens of stellar evolution: in honour of Franca D'Antona tenutosi a Monte Porzio Catone (Italy) nel 2012.

The flattening of globular clusters : internal rotation or velocity anisotropy?

G. Bertin;
2013

Abstract

Internal rotation is considered to play a major role in determining the structure and dynamics of some globular clusters. We present a dynamical analysis of the photometry and three-dimensional kinematics of 47 Tuc and ω Cen, by means of a new family of self-consistent axisymmetric rotating models. The combined use of line-of-sight velocities and proper motions allows us to obtain a global description of the internal dynamical structure of the objects together with an estimate of their dynamical distances. The well-relaxed cluster 47 Tuc is very well interpreted by our dynamical models; in particular, internal rotation is found to explain the observed morphology. For the partially relaxed cluster ω Cen, the selected model provides a good representation of its complex three-dimensional kinematics, in general qualitative agreement with the observed anisotropy profile, which is characterized by tangential anisotropy in the outer parts; discrepancies are found between the observed and the expected ellipticity profile and are ascribed to the presence of a high degree of radial anisotropy in the intermediate region and to its interplay with rotation.
globular clusters:general; globular clusters:individual: NGC 104 (47 Tuc); NGC 5139 (ω Cen)
Settore FIS/05 - Astronomia e Astrofisica
2013
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/479445
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