相关论文: A New Formula Describing the Scaffold Structure of…
Spiral galaxies are common in the local Universe, but their formation, evolution, and interplay with bars remain poorly understood. We use a sample of 391 nearby galaxies from the S$^4$G survey to characterise the winding angle and…
A method which we have developed for determining corotation radii, has allowed us to map in detail the radial resonant structures of barred spiral galaxies. Here we have combined this information with new determinations of the bar strength…
In order to establish an objective framework for studying galaxy morphology, we have developed a quantitative two-parameter description of galactic structure that maps closely on to Hubble's original tuning fork. Any galaxy can be placed in…
We measure the pitch angle ($\varphi$) of spiral arms in a sample of 79 galaxies to perform a systematic study of the dependence of $\varphi$ on galaxy morphology, mass, and kinematics to investigate the physical origin of spiral arms. We…
The frequency of barred spiral galaxies as a function of redshift contains important information on the gravitational influence of stellar disks in their dark matter halos and also may distinguish between contemporary theories for the…
We built a family of non-axisymmetric potential models for normal non-barred or weakly-barred spiral galaxies as defined in the simplest classification of galaxies: the Hubble sequence. For this purpose a three-dimensional self-gravitating…
Spiral galaxies are observed to exhibit a range of morphologies, in particular in the shape of spiral arms. A key diagnostic parameter is the pitch angle, which describes how tightly wound the spiral arms are. Observationally and…
We introduce a new approach to classify barred galaxies that utilizes the transverse-to-radial force ratio map (ratio map, hereafter) in a different manner from previous studies. When we display the ratio map in polar coordinates, barred…
We present data for a sample of 45 spiral galaxies over a range of Hubble types, imaged in the near-IR J and K bands. Parameters are calculated describing the bulge, disk and bar K-band light distributions, and we look for correlations…
We use classifications provided by citizen scientists though Galaxy Zoo to investigate the correlation between bulge size and arm winding in spiral galaxies. Whilst the traditional spiral sequence is based on a combination of both measures,…
We have imaged a sample of 45 face-on spiral galaxies in the K-band, to determine the morphology of the old stellar population, which dominates the mass in the disk. The K-band images of the spiral galaxies have been used to calculate…
We have compared the morphological characteristics of the 891 galaxies in the Extended 12-micron Sample (E12GS), and assessed the effect of the 12-micron selection criterion on galaxy properties. The normal spirals in the E12GS have the…
We propose a new theory to explain the formation of spiral arms and of all types of outer rings in barred galaxies. We have extended and applied the technique used in celestial mechanics to compute transfer orbits. Thus, our theory is based…
Rings and spiral arms are distinctive features of many galaxies, and their properties are closely related to the disk dynamics. They are often associated to stellar bars, but the details of this connection are far from clear. We study the…
We built models for low bulge mass spiral galaxies (late type as defined by the Hubble classification) using a 3-D self-gravitating model for spiral arms, and analyzed the orbital dynamics as a function of pitch angle, going from 10$\deg$…
Morphology is the starting point for understanding galaxies. Elmegreen et al. classified spiral galaxies into flocculent, multiple-arm, and grand-design galaxies based on the regularity of their spiral arm structure. With the release of a…
We propose a new, more realistic, description of the perturbed gravitational potential of spiral galaxies, with spiral arms having Gaussian-shaped groove profiles. We investigate the stable stellar orbits in galactic disks, using the new…
Spiral structure is ubiquitous in the Universe, and the pitch angle of arms in spiral galaxies provide an important observable in efforts to discriminate between different mechanisms of spiral arm formation and evolution. In this paper, we…
The apparent shapes of spiral galaxies in the 2-Micron All Sky Survey Large Galaxy Atlas are used to constrain the intrinsic shape of their disks. When the distribution of apparent axis ratios is estimated using a nonparametric kernel…
We propose a theory to explain the formation of both spirals and rings in barred galaxies using a common dynamical framework. It is based on the orbital motion driven by the unstable equilibrium points of the rotating bar potential. Thus,…