排序方式: 共有14条查询结果,搜索用时 93 毫秒
11.
E. Pignatelli E. M. Corsini J. C. Vega Beltrán C. Scarlata A. Pizzella J. G. Funes S. J. W. W. Zeilinger J. E. Beckman F. Bertola 《Monthly notices of the Royal Astronomical Society》2001,323(1):188-210
We present V -band surface photometry and major-axis kinematics of stars and ionized gas of three early-type spiral galaxies, namely NGC 772, 3898 and 7782. For each galaxy we present a self-consistent Jeans model for the stellar kinematics, adopting the light distribution of bulge and disc derived by means of a two-dimensional parametric photometric decomposition. This allows us to investigate the presence of non-circular gas motions, and derive the mass distribution of luminous and dark matter in these objects.
NGC 772 and 7782 have apparently normal kinematics with the ionized gas tracing the gravitational equilibrium circular speed. This is not true in the innermost region (| r |≲8 arcsec) of NGC 3898, where the ionized gas is rotating more slowly than the circular velocity predicted by dynamical modelling. This phenomenon is common in the bulge-dominated galaxies for which dynamical modelling enables us to make the direct comparison between the gas velocity and the circular speed, and it poses questions about the reliability of galaxy mass distributions derived by the direct decomposition of the observed ionized-gas rotation curve into the contributions of luminous and dark matter. 相似文献
NGC 772 and 7782 have apparently normal kinematics with the ionized gas tracing the gravitational equilibrium circular speed. This is not true in the innermost region (| r |≲8 arcsec) of NGC 3898, where the ionized gas is rotating more slowly than the circular velocity predicted by dynamical modelling. This phenomenon is common in the bulge-dominated galaxies for which dynamical modelling enables us to make the direct comparison between the gas velocity and the circular speed, and it poses questions about the reliability of galaxy mass distributions derived by the direct decomposition of the observed ionized-gas rotation curve into the contributions of luminous and dark matter. 相似文献
12.
J.C. Vega Beltrán E. Pignatelli W.W. Zeilinger A. Pizzella E.M. Corsini F. Bertola J.E. Beckman 《Astrophysics and Space Science》2001,276(2-4):509-516
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).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
W.W. Zeilinger J.C. Vega Beltrán M. Rozas J.E. Beckman A. Pizzella E.M. Corsini F. Bertola 《Astrophysics and Space Science》2001,276(2-4):643-650
The spiral galaxy NGC 3521 exhibits apparently normal kinematic properties of gas and stars along its major axis. However,
the analysis of the LOSVD reveals strong asymmetries. A decomposition of the LOSVD data with a two-Gaussian component model
shows two counter-rotating stellar components. The observed kinematic decoupling is interpreted as a projection effect induced
by the presence of a bar component seen almost end on. The bar produces locally a greater concentration of retrograde stellar
orbits but this does not relate to a specific counter-rotating population. The signatures of the bar are identified in the
velocity field derived from long-slit spectra obtained along the major, minor and 45° intermediate axes and from R-band surface photometry.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
M. Sarzi F. Bertola M. Cappellari E.M. Corsini J.G. S.J. Funes A. Pizzella J.C. Vega Beltrán 《Astrophysics and Space Science》2001,276(2-4):467-473
The R-band isophotal map of the Sa galaxy NGC 4698 shows that the inner region of the bulge is elongated perpendicularly to the
major axis of the disc. At the same time a central stellar velocity gradient is found along the minor axis of the disc. The
same properties have also been recognized in the Sa galaxy NGC 4672. This remarkable geometric and kinematic decoupling is
a direct indication that a second event occurred in the history of these galaxies suggesting that acquisition phenomena could
play a primary role in the formation of early-type spirals.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献