Subsystems of the Galactic halo, their structures and compositions


  • V. A. Marsakov Space Research Department at Rostov State University, Russian Federation
  • T. V. Borkova Space Research Department at Rostov State University, Russian Federation


Ключові слова:

globular clusters, Galaxy, abundances, halo


It is shown that general populations of globular clusters and metal-poor field stars are components at least of three subsystems occupying different volumes in the Galaxy. The thick disk and proto-disk subsystems are genetically associated with the Galaxy. The age distributions of these two subsystems do not overlap. It is argued that heavy-element enrichment and the collapse of the proto-galactic medium occurred mainly in the period between the formation of the proto-disk halo and thick disk subsystems. The largest third subsystem has no metallicity gradient, most of its objects have retrograde motion in the Galaxy, some of them have unusually low content of a-elements, and their ages are comparatively low in average, supporting the hypothesis that the objects in this subsystem had an extragalactic origin.


Allen A., Santillan A., 1991, Rev. Mex. Aston. Asroph., 22, 225

Borkova T.V., Marsakov V.A., 2000, Astron Zh,77, 750 (2000, Astron. Rep, 44, 665)

Borkova T.V., Marsakov V.A., 2002, Astron Zh,79, 510, (2002, Astron Rep, 46, 460)

Carney B.W., 1996, PASP, 108, 900

Da Costa G.S., Armandroff TE, 1995, AJ,109. 2533

Dambis A.K., Rastorguev A.S., 2001, AstL, 109, 2533

Eggen O.L, Lynden-Bell D.. Sandage A., 1962, ApJ, 136, 748

Hanson R.B., Sneden C., Kraft R.P. and Fulbright J., 1998, AJ, 116, 1286

Harris W.E., 1996, AJ, 112, 1487 (rev. 22 June 1999)

Hartwick F.D.A., 1987, in the Galaxy, Ed. By G.Gilmore and B.Carwell (Dordrech t), p.281

Ibata R.A., Gilmore G., Irvin M.J., 1994, Nature, 370, 194

Ivesic Z., et al 2000, AJ, 120, 963

Lauden A.C., AJ, 1994, 108, 1016

Majewski S.R., ApJ, 1992, 78, 87

Marsakov V.A., Suchkov A.A., 1977, Astron Zh, 54, 1232 [Sov Astron, 21, 700]

Marsakov V.A., Suchkov A.A., 1978, Astron Zh, 55, 472 [Sov Astron, 22, 700]

Mironov A.V., Samus N.N., 1974, Perem. Zvezdy, 19, 337

Nissen P.E., Schuster W.J., 1997, Aap, 251, 457

Reid I.N., 1997, AJ, 114, 161

Travaglio C., Galli D., Gallino R, et. al, 1999, ApJ, 521, 691

Wise R.F.G., Gilmore G., 1988, A], 95, 1404

Yoshii Y., Tsujimoto T., Nomoto K,, 1996, ApJ, 462, 266

Zirm R., 1985, ApJ, 293, 424

Zinn R., 1993, in The Globular Clusters-Galaxy Connection, Ed. By H. Smith and J. Brodee, ASP Conf. Ser., 48, 38