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Spiral galaxy - Wikipedia

en.wikipedia.org/wiki/Spiral_galaxy

A spiral galaxy is a type of galaxy originally described by Edwin Hubble in his 1936 work The ... found in low-density regions and are rare in the centers of galaxy clusters. ... blue stars (due to ...

Black Hole Active Galaxies and Quasars - Outer Space Central.com

www.outerspacecentral.com/agn_page.html

Some active galaxies have jets emanating from two sides of the center. ... 87 ( M87 for short or NGC 4486) a very active "radio" galaxy in the Virgo Cluster. ... Synchrotron radiation originates from collisions of electrons and positrons .... But blazars are fairly rare among active nuclei, with only about 2,700 known at this ...

Galaxies - Astronomy Notes

www.astronomynotes.com/galaxy/s10.htm

May 1, 2013 ... This explains why galaxies are grouped in clusters and even clusters ... the elliptical galaxies while the lower density concentrations would ... stars that star- star collisions are very rare when the galaxies collide. ... found close to the centers of galaxies were formed from the collision and merging of galaxies.

Star Clusters and Stellar Dynamics

www.astro.caltech.edu/~george/ay20/Ay20-Lec15x.pdf

globular star clusters, galaxies, clusters of galaxies. • If 2-body ... Sometimes stars actually collide, but that happens only in the ... density distribution function, f(r,v,t) ... In a large stellar system, gravitational force at any point due .... the orbit than rare close encounters… .... of energy in the center, to replace the esc...

Galaxies, Properties in Relation to Environment - NED

ned.ipac.caltech.edu/level5/ESSAYS/Dressler/dressler.html

Galaxies cluster; although a small fraction live in splendid isolation, the ... million light-years); therefore, encounters between galaxies are relatively rare. ... (as would be common in a rich cluster) because a low-speed collision would ... Furthermore, the fact that the stellar density at the center of an elliptical galaxy is typi...

Chapter 15 | SixDay Science

sixdayscience.com/curriculum/textbooks/chapter-15/

Also, large-scale structure is covered (galaxy clusters and collisions and superclusters). ... and be a regular spiral where the arms come right out of the galaxy center, ... The flattened shape is not due to rotational flattening but to how the orbits ... by the galaxy moving quickly through the low-density intergalactic medium (hot, ...

Introduction to Physical Astronomy - Galaxies

kias.dyndns.org/astrophys/galaxies.html

Note that the classification of a given galaxy is not always universally agreed ... Most disc stars in our galaxy have completed over 40 orbits around the galactic center. ... Near IR (1-5 μm) is due mostly to red giants, so it tracks mass; blue light is .... Collisions between galaxies in a cluster are much more frequent than those  ...

Gravity, Part 4: Globular Clusters & Galaxies. - University of Michigan

www.umich.edu/~lowbrows/reflections/2006/dsnyder.19.html

Jan 25, 2016 ... Gravity, Part 4: Globular Clusters & Galaxies: The dynamics of globular ... all stars in the cluster move in Kepler orbits around the center of mass. ... the expected velocity of stars in a region based on the density in that ... Astronomers used to believe physical collisions between stars were extremely rare and ...

Stripped Spirals and Cosmic Cannibals - NASA History Homepage

history.nasa.gov/SP-466/ch21.htm

In sharp contrast are the spiral galaxies nearer to the center of the cluster. ... This trend continues into the core of the cluster, where spirals are rare. ... It seems to have been related to the efficiency with which stars were born ... They have shown that Virgo and other rich clusters are pervaded by a very hot low density gas.

Cluster of Galaxies | NASA

www.nasa.gov/multimedia/imagegallery/image_feature_968.html

The constellation of Virgo (The Virgin) is especially rich in galaxies, due in part to the ... Gravitational interactions — from glancing blows to head-on collisions, tidal ...... greater density and show a strong concentration toward the galaxy's center. ..... Or, they may be very rare objects that formed in a region or period of t...