相关论文: Bars within Bars in Galaxies

I briefly review the properties of the gas flow in and around the region of the bar in a disc galaxy and discuss the corresponding inflow and the loci of star formation. I then review the flow of gas in barred galaxies which have an…

We present a deep near-infrared wide-angle photometric analysis of the structure of the inner Galactic bar and central disk. The presence of a triaxial structure at the centre of the Galaxy is confirmed, consistent with a bar inclined at…

We review general observational properties of bars in galaxies, and relations between bars, their dynamics, and (circum)nuclear activity. We consider new measurements of bar fractions and of the distribution of bars with host type, bar…

We establish a dynamical mechanism to explain the origin of the asymmetry between the arms observed in some barred disk galaxies, where one of the two arms emanating from the bar ends is very well defined, while the second one displays a…

We discuss different aspects of nested bar systems, both observational and theoretical. Such systems consist of a large-scale primary bar leading to the formation of a sub-kpc size secondary bar, whose pattern speed differs substantially…

In a series of papers, we propose a theory to explain the formation and properties of rings and spirals in barred galaxies. The building blocks of these structures are orbits guided by the manifolds emanating from the unstable Lagrangian…

Many of the stars in the Galaxy were formed in binary systems. The widest of these can eventually become disrupted due to a combination of kicks from passing stars and the Galactic tidal field. If the Galactic disk were purely axisymmetric,…

Two-armed, grand design spirals and inner and outer rings in barred galaxies can be due to orbits guided by the manifolds emanating from the vicinity of the L1 and L2 Lagrangian points, located at the ends of the bar. We first summarise the…

Double bars make up a significant fraction of barred galaxies. We propose a new formation scenario for double bars that involves tidal interactions. We demonstrate the viability of this scenario using two examples of simulated galaxies from…

I review some of the work on bars which is closely linked to the bar/bulge system in our Galaxy. Several independent studies, using totally independent methods, come to the same results about the 3D structure of a bar, i.e., that a bar is…

Numerical simulations of double-barred galaxies predict the build-up of different structural components (e.g., bulges, inner discs) in the central regions of disc galaxies. In those simulations, inner bars have a prominent role in the…

We propose a new dynamical mechanism to account for the bar off-centering observed in many barred galaxies. It is based on the presence of a m=1 density wave, non-linearly excited by the strong m=2 component due to the linearly unstable bar…

In this paper we present building blocks which can explain the formation and properties both of spirals and of inner and outer rings in barred galaxies. We first briefly summarise the main results of the full theoretical description we have…

Simulations and observations of galactic bars suggest they do not commonly evolve into bulges, although it is possible that the earliest bars formed bulges long ago, when galaxies were smaller, denser, and had more gas. The most highly…

We review the observational evidences concerning the three-dimensional structure of the Galactic bulge. Although the inner few kpc of our Galaxy are normally referred to as {\it the bulge}, all the observations demonstrate that this region…

Spiral arms that emerge from the ends of a galactic bar are important in interpreting observations of our and external galaxies. It is therefore important to understand the physical mechanism that causes them. We find that these spiral arms…

Gas flows in the presence of two independently-rotating nested bars remain not fully understood, which is likely to play an important role in fueling the central black hole. We use high-resolution hydrodynamical simulations with detailed…

(Abridge) Bars are very common in the centre of the disc galaxies, and they drive the evolution of their structure. A volume-limited sample of 2106 disc galaxies extracted from the Sloan Digital Sky Survey Data Release 5 was studied to…

Galactic bars can form via the internal bar instability or external tidal perturbations by other galaxies. We systematically compare the properties of bars formed through the two mechanisms with a series of controlled $N$-body simulations…

Using hydrodynamic simulations, we investigate the physical properties of gaseous substructures in barred galaxies and their relationships with the bar strength. The gaseous medium is assumed to be isothermal and unmagnetized. The bar…