EDP Sciences
Free access
Volume 419, Number 2, May IV 2004
Page(s) 449 - 458
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20034302

A&A 419, 449-458 (2004)
DOI: 10.1051/0004-6361:20034302

The elliptical galaxy NGC 5044: Stellar population and ionized gas

M. G. Rickes, M. G. Pastoriza and Ch. Bonatto

Universidade Federal do Rio Grande do Sul (UFRGS), Instituto de Física, Departamento de Astronomia, Brasil
    e-mail: [maurogr;mgp]@if.ufrgs.br
(Received 10 September 2003 / Accepted 16 February 2004)

In this work we investigate the stellar population, metallicity distribution and ionized gas in the elliptical galaxy NGC 5044, using long-slit spectroscopy and a stellar population synthesis method. We found differences in the slope of metal-line profiles along the galaxy which suggests an enhancement of $\alpha$ elements, particularly towards the central region. The stellar population synthesis showed that the component with $[Z/Z_\odot]\sim0.0$ dominates the $\lambda5870$ Å flux in the central region of NGC 5044, contributing with ~ $42\%$ of the total flux, while in the external regions the contribution decreases to ~ $8.0\%$. The component with $[Z/Z_\odot]\sim-0.4$ contributes with ~ $32\%$ in the central region, and ~ $55\%$ in the external regions. The component with $[Z/Z_\odot]\sim-1.1$ contributes with ~ $26\%$ in the central region, and ~ $37\%$ in the external regions. The three components have ~ 1010 years. The presence of a non-thermal ionization source, such as a low-luminosity AGN and/or shock ionization, is implied by the large values of the ratio $\frac{\ion{[N}{ii]}}{\rm H\alpha}$ observed in all sampled regions. However, the emission lines observed in the external regions indicate the presence of an additional ionization source, probably hot, post-AGB stars.

Key words: galaxies: elliptical and lenticular, cD -- galaxies: individual: NGC 5044 -- galaxies: fundamental parameters

Offprint request: Ch. Bonatto, charles@if.ufrgs.br

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