Bibcode
Vega Beltrán, J. C.; Pignatelli, E.; Zeilinger, W. W.; Pizzella, A.; Corsini, E. M.; Bertola, F.; Beckman, J. E.
Referencia bibliográfica
Astrophysics and Space Science, v. 276, Issue 2/4, p. 509-516 (2001).
Fecha de publicación:
3
2001
Revista
Número de citas
0
Número de citas referidas
0
Descripción
We present a comparison between the ionized gas and stellar kinematics
for a sample of five early-to-intermediate disc galaxies. We measured
the major axis V and σ radial profiles for both gas and stars, and
the h_3 and h_4 radial profiles of the stars. We also derived from the
R-band surface photometry of each galaxy the light contribution of their
bulges and discs. In order to investigate the differences between the
velocity fields of the sample galaxies we adopted the self-consistent
dynamical model by Pignatelli and Galletta (1999), which takes into
account the asymmetric drift effects, the projection effects along the
line of sight and the non-Gaussian shape of the line profiles due to the
presence of different components with distinct dynamical behaviour. We
find for the stellar component a sizeable asymmetric drift effect in the
inner regions of all the sample galaxies, as results from comparing
their stellar rotation curves with the circular velocity predicted by
the models. The galaxy sample is not wide enough to draw general
conclusions. However, we have found a possible correlation between the
presence of slowly rising gas rotation curves and the ratio of the
bulge/disc half-luminosity radii, while there is no obvious correlation
with the key parameter represented by the morphological classification,
namely the bulge/disc luminosity ratio. Systems with a diffuse,
dynamically hot component (bulge or lens) with a scale length comparable
to that of the disc are characterized by slowly rising gas rotation
curves. On the other hand, in systems with a small bulge the gas follows
almost circular motions, regardless of the luminosity of the bulge
itself. We noticed a similar behaviour also in the gas and stellar
kinematics of the two early-type spiral galaxies modelled by Corsini et
al. (1998).