Bibcode
Pizzella, A.; Corsini, E. M.; Vega Beltrán, J. C.; Bertola, F.
Referencia bibliográfica
Astronomy and Astrophysics, v.424, p.447-454 (2004)
Fecha de publicación:
9
2004
Revista
Número de citas
90
Número de citas referidas
82
Descripción
Ionized gas and stellar kinematics have been measured along the major
axes of seventeen nearby spiral galaxies of intermediate to late
morphological type. We discuss the properties of each sample galaxy,
distinguishing between those characterized by regular or peculiar
kinematics. In most of the observed galaxies, ionized gas rotates more
rapidly than stars and has a lower velocity dispersion, as is to be
expected if the gas is confined in the disc and supported by rotation
while the stars are mostly supported by dynamical pressure. In a few
objects, gas and stars show almost the same rotational velocity and low
velocity dispersion, suggesting that their motion is dominated by
rotation. Incorporating the spiral galaxies studied by Bertola et al.
(cite{Bertola1996}), Corsini et al. (cite{Corsini1999},
cite{Corsini2003}) and Vega Beltrán et al. (cite{Vega2001}) we
have compiled a sample of 50 S0/a-Scd galaxies, for which the major-axis
kinematics of the ionized gas and stars have been obtained with the same
spatial (≈1'') and spectral (≈50 km;s-1) resolution,
and measured with the same analysis techniques. This allowed us to
address the frequency of counter-rotation in spiral galaxies. It turns
out that less than 12% and less than 8% (at the 95% confidence level) of
the sample galaxies host a counter-rotating gaseous and stellar disc,
respectively. The comparison with S0 galaxies suggests that the
retrograde acquisition of small amounts of external gas gives rise to
counter-rotating gaseous discs only in gas-poor S0s, while in gas-rich
spirals the newly acquired gas is swept away by the pre-existing gas.
Counter-rotating gaseous and stellar discs in spirals are formed only
from the retrograde acquisition of large amounts of gas exceeding that
of pre-existing gas, and subsequent star formation, respectively.
Based on observations carried out at the European Southern Observatory,
La Silla (Chile) (ESO 56.A-0684 and 57.A-0569).
Tables 3 and 4 are only available in electronic form at the CDS via
anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/424/447
Full Fig.
ef{fig:kinematics} and Figs.
ef{fig:gascomparison} and
ef{fig:starcomparison} are only available in electronic form at
http://www.edpsciences.org