On the relative frequency of flocculent and grand design spiral structures in barred galaxies

1989 ◽  
Vol 342 ◽  
pp. 677 ◽  
Author(s):  
Bruce G. Elmegreen ◽  
Debra Meloy Elmegreen
Keyword(s):  
Relative Frequency ◽  
Barred Galaxies ◽  
Grand Design ◽  
Spiral Structures ◽  
Design Spiral

scholarly journals Stellar Spirals in Triaxial Dark Matter Halos

2016 ◽  
Vol 11 (S321) ◽  
pp. 120-120
Author(s):  
Shaoran Hu ◽  
Debora Sijacki
Keyword(s):  
Dark Matter ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Grand Design ◽  
Spiral Structures ◽  
Design Spiral

AbstractTwo-armed grand-design spirals may form if the shape of its dark matter halo changes abruptly enough. The feasibility of such a mechanism is tested in realistic simulations. The interplay of such externally-driven spirals and self-induced transient spirals is then studied. Subhaloes are also found to lead to transient grand-design spiral structures when they impact the disk.

scholarly journals Formation and maintenance of spiral structure in galaxies

1985 ◽  
Vol 106 ◽  
pp. 513-532 ◽  
Author(s):  
C. C. Lin ◽  
G. Bertin
Keyword(s):  
Spiral Structure ◽  
Future Research ◽  
Barred Galaxies ◽  
Propagating Waves ◽  
Grand Design ◽  
Spiral Structures ◽  
Proper Perspective

The formation and maintenance of spiral structure in galaxies is discussed in terms of spiral modes with a general perception consistent with the hypothesis of quasi-stationary spiral structure. The latter is explained in some detail to give it the original proper perspective and to contrast it with recent studies of non-stationary spiral structures. We again emphasize the possible coexistence of fast-evolving spiral features and slow-evolving spiral grand designs. Spiral modes are described in terms of three categories of propagating waves. The reason is given why isolated non-barred galaxies with spiral grand design are found to be mostly two-armed. Some suggestions are made for future research.

Observational Manifestation of Chaos in Grand Design Spiral Galaxies

2003 ◽  
pp. 223-234 ◽  
Author(s):  
Alexei M. Fridman ◽  
Roald Z. Sagdeev ◽  
Oleg V. Khoruzii ◽  
Evgenii V. Polyachenko
Keyword(s):  
Spiral Galaxies ◽  
Grand Design ◽  
Observational Manifestation ◽  
Design Spiral

scholarly journals H II Region Statistics in Barred and Non-Barred Galaxies

1996 ◽  
Vol 157 ◽  
pp. 114-116
Author(s):  
M. Rozas ◽  
J. E. Beckman ◽  
J. H. Knapen
Keyword(s):  
Hii Regions ◽  
Statistical Properties ◽  
High Quality ◽  
Hii Region ◽  
Barred Galaxies ◽  
Density Distributions ◽  
Luminosity Functions ◽  
Grand Design ◽  
H Ii Region

AbstractWe present new high quality Ha continuum-subtracted images of the grand design galaxies NGC 157, NGC 3631, NGC 6764, and NGC 6951, two of them barred and two non-barred, and describe the statistical properties of the HII regions. We have determined the positions, angular sizes and fluxes of individual HII regions, and construct luminosity functions and diameter and density distributions. We find no significant differences between arm and interarm HII region properties, or between the barred and non-barred galaxies. This paper summarizes work described in more detail by Rozas et al. (1995a,b)

scholarly journals Young stellar clusters triggered by a density wave in NGC 2997

2006 ◽  
Vol 2 (S237) ◽  
pp. 417-417
Author(s):  
P. Grosbøl ◽  
H. Dottori ◽  
R. Gredel
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Density Wave ◽  
Star Formation History ◽  
Stellar Clusters ◽  
Star Forming ◽  
Continuous Formation ◽  
Grand Design ◽  
K Band ◽  
Design Spiral

AbstractBright knots along the arms of grand-design spiral galaxies are frequently seen on near-infrared K-band images. To investigate their nature, low resolution K-band spectra of a string of knots in the southern arm of the grand design, spiral galaxy NGC 2997 were obtained with ISAAC/VLT. Most of the knots show strong Brγ emission while some have H2 and HeI emission. A few knots show indications of CO absorption. Their spectra and absolute K magnitudes exceeding -12 mag suggest them to be very compact, young stellar clusters with masses up to 5 × 104 M. The knots' azimuthal distance from the K-band spiral correlates well with their Brγ strength, indicating that they are located inside the co-rotation of the density wave, which triggered them through a large-scale, star-forming front. These relative azimuthal distances suggest an age spread of more than 1.6 Myr, which is incompatible with standard models for an instantaneous star burst. This indicates a more complex star-formation history, such as several bursts or continuous formation.

scholarly journals Observations of Galactic Magnetic Fields

2002 ◽  
Vol 12 ◽  
pp. 712-715 ◽  
Author(s):  
Rainer Beck
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Density Wave ◽  
Upstream Region ◽  
Galactic Magnetic Fields ◽  
Barred Galaxies ◽  
Angular Momentum Transport ◽  
Central Regions ◽  
Spiral Structures ◽  
Field Lines

AbstractMagnetic fields are anchored in gas clouds. Field lines are tangled in spiral arms, but highly regularbetweenthe arms. The similarity of pitch angles between gaseous and magnetic arms suggests a coupling between the density wave and the magnetic wave. Observations of large-scale patterns in Faraday rotation favour a dynamo origin of the regular fields. Fields in barred galaxies do not reveal the strong shearing shocks observed in the cold gas, but swing smoothly from the upstream region into the bar. Magnetic fields are important for the dynamics of gas clouds, for the formation of spiral structures, bars and halos, and for mass and angular momentum transport in central regions.

scholarly journals Outer spiral structure in disk galaxies

2016 ◽  
Vol 11 (S321) ◽  
pp. 123-123
Author(s):  
P.A. Patsis
Keyword(s):  
Periodic Orbits ◽  
Spiral Galaxies ◽  
Spiral Structure ◽  
Disk Galaxies ◽  
Spiral Arms ◽  
Chaotic Orbits ◽  
Grand Design ◽  
Pattern Speed ◽  
Spiral Structures ◽  
Barred Spiral Galaxies

AbstractIn several grand design barred-spiral galaxies it is observed a second, fainter, outer set of spiral arms. Typical examples of objects of this morphology can be considered NGC 1566 and NGC 5248. I suggest that such an overall structure can be the result of two dynamical mechanisms acting in the disc. The bar and both spiral systems rotate with the same pattern speed. The inner spiral is reinforced by regular orbits trapped around the stable, elliptical, periodic orbits of the central family, while the outer system of spiral arms is supported by chaotic orbits. Chaotic orbits are also responsible for a rhomboidal area surrounding the inner barred-spiral region. In general there is a discontinuity between the two spiral structures at the corotation region.

scholarly journals J1649+2635: a grand-design spiral with a large double-lobed radio source

2014 ◽  
Vol 446 (4) ◽  
pp. 4176-4185 ◽  
Author(s):  
Minnie Y. Mao ◽  
Frazer Owen ◽  
Ryan Duffin ◽  
Bill Keel ◽  
Mark Lacy ◽  
...  
Keyword(s):  
Radio Source ◽  
Grand Design ◽  
Design Spiral
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