[en] Based on a model of globular cluster self-enrichment published in a previous paper, we present an explanation for the metallicity gradient observed throughout the galactic Old Halo. Our self-enrichment model is based on the ability of globular cluster progenitor clouds to retain the ejecta of a first generation of Type II Supernovae. The key point is that this ability depends on the pressure exerted on the progenitor cloud by the surrounding protogalactic medium and therefore on the location of the cloud in the protoGalaxy. Since there is no significant (if any) metallicity gradient in the whole halo, we also present a review in favour of a galactic halo partly built via accretions and mergers of satellite systems. Some of them bear their own globular clusters and therefore ``contaminate'' the system of globular clusters formed ``in situ'', namely within the original potential well of the Galaxy. Therefore, the comparison between our self-enrichment model and the observational data should be limited to the genuine galactic globular clusters, the so-called Old Halo group.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Parmentier, Geneviève ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Jehin, Emmanuel ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Magain, Pierre ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Noels-Grötsch, Arlette ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)
Thoul, Anne ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Evol. et stabilité des étoiles et des amas d'étoiles (ESEA)
Language :
English
Title :
The Old Halo metallicity gradient: the trace of a self-enrichment process
Chaboyer B., Demarque P., Sarajedini A., 1996, ApJ 459, 558
Chiba M., 2000, In: Weiss A., Abel T., Hill V. (eds.) Proceedings of the 2nd ESO/MPA Conference, The First Stars. Springer, p. 77
Côté P., 1999, AJ 118, 406
Da Costa G.S., 1993, In: Smith G.H., Brodie J.P. (eds.) ASP Conf. Ser. Vol. 48, The globular clusters-galaxy connection, p. 363
Da Costa G.S., Armandroff T.E., 1995, AJ 109, 2533
Dinescu D.I., Girard T.M., Van Altena W.F., 1999, AJ 117, 1792
Djorgovski S., Meylan G., 1994, AJ 108, 1292
Eggen O.J., Lynden-Bell D., Sandage A., 1962, ApJ 136, 748
Elson R.A.W., Fall S.M., 1988, AJ 96, 1383
Fabricant D., Lecar M., Gorenstein P., 1980, ApJ 241, 552
Fall S.M., Rees M.J., 1985, ApJ 298, 18
Ferraro I., Ferraro F.R., Fusi Pecci F., Corsi C.E., Buonanno R., 1995, MNRAS 275, 1057
Freeman K.C., Norris J., 1981, ARA&A 19, 319
Fusi Pecci F., Bellazini M., Cacciari C., Ferraro F.R., 1995, AJ 110, 1664
Harris W.E., Pudritz R.E., 1994, ApJ 429, 177
Harris W.E., 1996, AJ 112, 1487
Harris W.E., Bell R.A., Vandenberg D.A., et al., 1997, AJ 114, 1030
Hartwick F.D.A., 1987, In: The Galaxy. Proceedings of the NATO Advanced Study Institute, Cambridge, England, D. Reidel Publishing Co., Dordrecht, p. 281
King I.R., 1999, In: Martinez Roger C., Pérez Fournon I., Sanchez F. (eds.) Globular Clusters, CUP, p. I
Larson R.B., 1992, In: Tenorio-Tagle G., Prieto M., Sanchez F. (eds.) Star Formation in Stellar System, CUP, p. 143
Lee Y.W., 1993, In: Smith G.H., Brodie J.P. (eds.) ASP Conf. Ser. Vol. 48, The globular clusters-galaxy connection, p. 142
Lee Y.W., Demarque P., Zinn R., 1994, ApJ 423, 248
Lin D.N.C., Richer H.B., 1992, ApJ 388, L57
Majewski S.R., 1992, ApJS 78, 87
Majewski S.R., 1994, ApJ 431, L17
Majewski S.R., 2000, In: A. Noels, P. Magain, D. Caro, et al., (eds.) 35th Liège International Astrophysics Colloquium, The galactic halo: from globular clusters to field stars, p. 619
Marquez A., Schuster W.J., 1994, A&AS 108, 341
Mateo M., 1998, ARA&A 36, 435
Meylan G., Heggie D.C., 1997, A&AR 8, 1
Meylan G., 2000, In: Noels A., Magain P., Caro D., et al. (eds.) 35th Liège International Astrophysics Colloquium, The galactic halo: from globular clusters to field stars, p. 543
Meziane K., Colin J., 1996, A&306, 747
Mighell K.J., Rich R.M., Shara M., Fall S.M., 1996, AJ 111, 2314
Minniti D., 1995, AJ 109, 1663
Murray S.D., Lin D.N.C., 1992, ApJ 400, 265
Odenkirchen M., Brosche P., Geffert M., Tucholke H.-J., 1997 New Astronomy 2, 477
Parmentier G., Jehin E., Magain P., et al., 1999, A&A 352, 138