Hostname: page-component-5c6d5d7d68-thh2z Total loading time: 0 Render date: 2024-08-17T19:44:07.286Z Has data issue: false hasContentIssue false
  • English
  • Français

Chemical Evolution of Elliptical Galaxies: Mg2 Gradients and G-Dwarf Problem

Published online by Cambridge University Press:  14 August 2015

N. Arimoto  and
C. Kobayashi
N. Arimoto
Affiliation:
Institute of Astronomy, University of Tokyo Mitaka, Tokyo 181, Japan
C. Kobayashi
Affiliation:
Department of Astronomy, School of Science, University of Tokyo Yayoi, Bunkyo-ku, Tokyo 113, Japan

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Stellar populations of elliptical galaxies were studied extensively in the recent past (eg., Arimoto & Yoshii 1987; Buzzoni et al. 1992; Worthey 1994; Kodama & Arimoto 1997). However, colours and line-strengths analysed by these approaches came mainly from central regions of galaxies and possible variations of stellar population structure within a galaxy were entirely ignored. Kodama & Arimoto (1997) recently show that a colour-magnitude (CM) relation of ellipticals in Coma cluster (Bower, Lucey, & Ellis 1992), and the CM relation of cluster ellipticals in general, should originate from a difference in mean stellar metallicities, as suggested by Arimoto & Yoshii (1987), and cannot be due to an increase of mean stellar age towards luminous galaxies as claimed by Worthey (1994). It is quite often stated that any theory of galaxy formation should explain the origin of CM relation, or in other words, the mass (luminosity) - metallicity relation of elliptical galaxies. However, one should not forget the fact that the CM relation is defined only for stars in the central regions of galaxies; it is possible that the CM relation itself is an observational artifact, since ellipticals show in general radial gradients of metallic-line strengthes, decreasing from a centre towards outer regions (eg., Faber 1977; Davies, Sadler, & Peletier 1993; Gonzalez 1993; Carollo & Danziger 1994). Indeed, Gorgas & Gonzalez (1996) found that ellipticals with larger central Mg2 indices tend to have steeper Mg2 gradient, which suggests that global metallicities of ellipticals are perphaps universal and are independent of galaxy luminosities.

Type
II. Joint Discussions
Information
Highlights of Astronomy , Volume 11 , Issue 1: Highlights of Astronomy. As presented at the XXIIIrd General Assembly of the IAU (Part A), 1997 , 1998 , pp. 74 - 77
Copyright
Copyright © Kluwer 1998

References

Arimoto, N., Matsushita, K., Ishimaru, Y., Ohashi, T., & Renzini, A., 1997, ApJ, 477, 128 Google Scholar
Arimoto, N. & Yoshii, Y., 1987, ASA, 173, 23 Google Scholar
Bower, R.G., Lucey, J.R., & Ellis, R.S., 1992, MNRAS, 254, 601 Google Scholar
Buzzoni, A., Gariboldi, G., & Mantegazza, L., 1992, AJ, 103, 1814 Google Scholar
Carollo, C.M., & Danziger, I.J., 1994, MNRAS, 270, 523 Google Scholar
Davies, R.L., Sadler, E.M., & Peletier, R.F., 1993, MNRAS, 262, 650 Google Scholar
Davies, R.L., Burstein, D., Dressier, A., Faber, S.M., Lynden-Bell, D., Terlevich, R.J., & Wegner, G., 1987, ApJS, 64, 581 Google Scholar
Faber, S.M., 1977, in The Evolution of Galaxies and Stellar Populations, eds., Tinsley, T. & Larson, R.B. (New Heaven: Yale Univ. Press) p.157 Google Scholar
Gonzalez, J.J., 1993, PhD thesis, Univ. of Califolnia Google Scholar
Gorgas, J., & Gonzalez, J.J., 1996, ASP Conference Series, 86, 225 Google Scholar
Kodama, T., & Arimoto, N., 1997, A&A, 320, 41 Google Scholar
Köppen, J., & Arimoto, N., 1990, A&A, 240, 22 Google Scholar
Worthey, G., 1994, ApJS, 95, 107 Google Scholar