Evidence for small halos in grand design spiral galaxies

1990 ◽  
Vol 364 ◽  
pp. 412 ◽  
Author(s):  
Debra Meloy Elmegreen ◽  
Bruce G. Elmegreen
Keyword(s):  
Spiral Galaxies ◽  
Grand Design ◽  
Design Spiral

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 Analysis of Resonances in Grand Design Spiral Galaxies

2001 ◽  
Vol 547 (1) ◽  
pp. 187-199 ◽  
Author(s):  
Nelson Vera‐Villamizar ◽  
Horacio Dottori ◽  
Ivanio Puerari ◽  
Reinaldo de Carvalho
Keyword(s):  
Spiral Galaxies ◽  
Grand Design ◽  
Design Spiral

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 Galactic spiral structure

2009 ◽  
Vol 465 (2111) ◽  
pp. 3425-3446 ◽  
Author(s):  
Charles Francis ◽  
Erik Anderson
Keyword(s):  
Pitch Angle ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Stellar Orbits ◽  
Grand Design ◽  
Galactic Spiral Structure ◽  
Pattern Speed ◽  
Galactic Spiral ◽  
Almost All ◽  
Spiral Arm

We describe the structure and composition of six major stellar streams in a population of 20 574 local stars in the New Hipparcos Reduction with known radial velocities. We find that, once fast moving stars are excluded, almost all stars belong to one of these streams. The results of our investigation have led us to re-examine the hydrogen maps of the Milky Way, from which we identify the possibility of a symmetric two-armed spiral with half the conventionally accepted pitch angle. We describe a model of spiral arm motions that matches the observed velocities and compositions of the six major streams, as well as the observed velocities of the Hyades and Praesepe clusters at the extreme of the Hyades stream. We model stellar orbits as perturbed ellipses aligned at a focus in coordinates rotating at the rate of precession of apocentre. Stars join a spiral arm just before apocentre, follow the arm for more than half an orbit, and leave the arm soon after pericentre. Spiral pattern speed equals the mean rate of precession of apocentre. Spiral arms are shown to be stable configurations of stellar orbits, up to the formation of a bar and/or ring. Pitch angle is directly related to the distribution of orbital eccentricities in a given spiral galaxy. We show how spiral galaxies can evolve to form bars and rings. We show that orbits of gas clouds are stable only in bisymmetric spirals. We conclude that spiral galaxies evolve toward grand design two-armed spirals. We infer from the velocity distributions that the Milky Way evolved into this form about 9 billion years ago (Ga).

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

scholarly journals Galactic spiral generation in tidal encounters

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Alex R. Pettitt ◽  
Elizabeth J. Tasker ◽  
James W. Wadsley
Keyword(s):  
Spiral Galaxies ◽  
Key Points ◽  
The Galaxy ◽  
Grand Design ◽  
Spiral Structures ◽  
Galactic Spiral ◽  
Morphological Differences ◽  
The Universe ◽  
Disc Galaxies ◽  
Real Universe

AbstractThe existence of grand design spiral galaxies in the universe is still a standing problem. The passage of a small companion is known to be able to induce spiral structures in disc galaxies, but there remains questions over how relevant this mechanism is to the galaxies observed in the real universe. Our study aims to address two key points regarding such interactions; the limiting mass companion needed to drive tidal spiral structures, and the differences between the resulting gas and stellar morphology. We find the minimum mass of a companion to be as low as 5% of the stellar mass of the galaxy, and that the arms formed in the gas and the stars display very minor dynamical and morphological differences.

Sign in / Sign up

Export Citation Format

Share Document