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

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The distribution of ionized gas in early-type galaxies

III. M /L determinations based on triaxial models *

A. Pizzella 1, P. Amico 2, F. Bertola 1, L.M. Buson 3, I.J. Danziger 2, 4, H. Dejonghe 5, E.M. Sadler 6, R.P. Saglia 7, P.T. de Zeeuw 8 and W.W. Zeilinger 9

1 Dipartimento di Astronomia, Università di Padova, Italy
2 European Southern Observatory, Garching bei München, Germany
3 Osservatorio Astronomico, Capodimonte, Napoli, Italy
4 Osservatorio Astronomico, Trieste, Italy
5 Sterrenkundig Observatorium, Universiteit Gent, Belgium
6 Astrophysics Department, School of Physics, Univ. of Sydney, Australia
7 Universitäts-Sternwarte München, Germany
8 Sterrewacht Leiden, The Netherlands
9 Institut für Astronomie, Universität Wien, Austria

Received 20 May 1996 / Accepted 2 January 1997


The velocity fields of ionized gas disks in four elliptical galaxies have been exploited to derive the mass-to-light ratios as function of radial distance. For each galaxy, namely NGC 1453, NGC 2974, NGC 5077 and NGC 7097, we derive a set of intrinsic shapes of the stellar component and viewing angles that are consistent with the observed ellipticities and orientation of the isophotes. A least-squares fit to the observed velocity field gives the set of parameters defining the potential that best reproduces the kinematics of the ionized gas disk as well as the mass density and light density radial profiles. For three galaxies a satisfactory model is found. The [FORMULA] ratio does change within individual galaxies, though not showing any systematic increase with radius and has a mean value of about 5 [FORMULA] out to [FORMULA].

Key words: galaxies: elliptical and lenticular, cD – galaxies: ISM – galaxies: structure – galaxies: kinematics and dynamics

* Based on observations collected at the European Southern Observatory, La Silla (Chile).

Send offprint requests to: Alessandro Pizzella, Dipartimento di Astronomia, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy (pizzella@astrpd.pd.astro.it)

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© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998