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Paper: Evidences of Axial Symmetry Rupture in the Solar Neighborhood
Volume: 316, Order and Chaos in Stellar and Planetary Systems
Page: 234
Authors: Alcobe, S.; Cubarsi, R.
Abstract: It is well known that population moments are good indicators of some features—such as symmetries—of the velocity distribution. The trivariate velocity distribution moments of representative local stellar samples from CNS3 and HIPPARCOS catalogs are evaluated, where a superposition of stellar populations is assumed. The samples have been selected looking for the maximum entropy of the mixture probability and a numerical-statistical algorithm has been applied for computing the partial kinematic parameters. In order to give an interpretation to the obtained results, some dynamic models based on Chandrasekhar's approximation are reviewed. According to those models, values of specific moments are different as expected for some of the stellar populations. In particular the moment μωθ, and also several odd-order moments, are clearly not null. The same statistical analysis is carried out for both star samples. For the closer one, derived from CNS3, a stellar component, associated with old disk stars, could fit in an axially symmetric model. Nevertheless, for the sample selected from HIPPARCOS, which takes a much larger scale height as CNS3, even in the case of a Galactic disk with three stellar components, all partial populations require at least point-axial symmetry in order to explain their kinematic behavior.
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