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Astron. Astrophys. 323, 349-356 (1997)

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1. Introduction

This is the third in a series of papers on the properties of elliptical galaxies with ionized gas disks that have been produced by the ESO Key Programme "A search for dark matter in elliptical galaxies" (Bertin et al. 1989). In Paper I (Buson et al. 1993) the [FORMULA] imaging for 15 galaxies known to have emission lines was presented and discussed. Follow up spectroscopic observations, which map the velocity field of the ionized gas, were made for six objects with regular gas morphology, and were presented in Paper II (Zeilinger et al. 1996). In this third paper we compare these datasets, three velocity fields from Paper II and one, NGC 5077, from Bertola et al. (1991, hereafter B91), with models for the non-circular velocity fields of cold gas in triaxial potentials. The models allow us to correlate the parameters related to the intrinsic shape of the galaxy with the observed ellipticity values and the position angle of the stellar major axis. The fits to the velocity field and to the luminosity profile give the mass and light density profiles respectively and hence the radial mass-to-light profile. The method is similar to that developed by de Zeeuw and Franx (1989, hereafter ZF) and applied by B91 to NGC 5077. Here we consider models with cusped central density profiles. The extension of the ionized gas disks is typically of the order of one effective radius, [FORMULA], or less. Our study is therefore limited to the inner regions of the galaxies.

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© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998