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Halo and high–velocity disk stars

Published online by Cambridge University Press:  07 August 2017

W. J. Schuster
Affiliation:
Instituto de Astronomía, UNAM. Apdo.P. 70-264, C.P. 04510, México, D.F. I.N.A.O.E. A.P. 51 y 216, C.P. 72000, Puebla, Pue. México
C. Allen
Affiliation:
Instituto de Astronomía, UNAM. Apdo.P. 70-264, C.P. 04510, México, D.F. D.G.S.C.A., UNAM. C.P. 04510, México, D.F.
A. Poveda
Affiliation:
Instituto de Astronomía, UNAM. Apdo.P. 70-264, C.P. 04510, México, D.F.

Abstract

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Using the uvby – β data of Schuster and Nissen (1988) to calculate photometric distances and using the galactic potentials of Allen and Martos (1986) and Allen and Santillán (1991), galactic orbits have been integrated for 615 halo and high-velocity disk stars. Correlations between orbital characteristics, metallicities, and ages are being studied. For the 206 halo stars of this sample, a particularly high percentage of the orbits (35-50%) show some chaotic behavior, due mainly to their low angular momenta which lead to small (< 1 Kpc) perigalactic distances. The newer potential of Allen and Santillán, which includes a spherical central bulge rather than a central mass point, gives the higher percentage of chaotic orbits. The effects of this chaos upon chemical gradients and upon the dynamical structure of the halo are being investigated.

Type
Poster Papers
Copyright
Copyright © Kluwer 

References

Allen, C., Martos, M.A. 1986, Rev Mex Astr Astrofis 13, 137147.Google Scholar
Allen, C. Santillán, A. 1991, Rev Mex Astr Astrofis (in press).Google Scholar
Schuster, W.J., Nissen, P.E. 1988, A&AS 73, 225241.Google Scholar