Spiral galaxies form from the collapse of a protogalactic cloud. Spiral galaxies consist of three components: a rotating disk, a bulge and a halo. Spiral galaxies, like the Milky Way, owe their shape to stars inside the protogalaxy developing at different intervals. The gas between forming stars continues to be compressed, and the resulting gravitational differences manhandle the protogalaxy's stars, dust and gas. When the protogalactic cloud collapses, the stars in the bulge and halo form first. These stars have rather random orbits around the galactic center. The galactic center probably contains a supermassive black hole, which likely exerts some gravitational influence on the formation of a spiral galaxy.
The remainder of the cloud forms a disk due to the conservation of angular momentum (the same effect as the spinning up of the dancer when she pulls her arms inside). This motion forces everything into a rotating disk, and additional differences in gravity build the spiral arms. Oppositely, when a protogalaxy's stars develop at the same time, you have an elliptical galaxy on your hands. The stars in the disk form later and thus the disk population of stars are younger than those in the bulge and the halo. Further, the stars in the disk rotate around the center of the galaxy in a collective, well defined way unlike the stars in the bulge and halo.
They are in space. (: you're welcome.
Spiral galaxies have a clearly defined disk component characterized by spiral arms, while lenticular galaxies have a disk without prominent spiral arms. Irregular galaxies may also have a disk component, but it is usually less organized than in spiral galaxies.
That is a difficult question to fully answer as types of galaxies are not fully defined. A ball park figure would be dwarf galaxies, or spiral galaxies depending on the area in question. See related question for a full breakdown.
Hubble devised subcategorization for spiral galaxies first based on whether the galaxy exhibited a bar and then how well the spiral arms were defined. The classes are designated as Sa, Sb, and SC with the Sa class being the most tightly wound. A capital B designation after the S indicates the presence of a bar as well.
There are generally three types of galaxies: spiral galaxies, elliptical galaxies, and irregular galaxies. Spiral galaxies like the Milky Way have a disk shape with arms of stars spiraling out from a central core. Elliptical galaxies are shaped like ellipses and contain mostly older stars. Irregular galaxies have a less defined shape and tend to have a mix of young and old stars.
Spiral galaxies, barred spiral galaxies, elliptical galaxies, and irregular galaxies
the three main types of galaxies are spiral, elliptical and irregular spiral contains spiral arms contained gas, dust and they help new stars form
While spiral galaxies are bright, elliptical galaxies are dim. Spiral galaxies are hotbeds of star formation, but elliptical galaxies aren't nearly as prolific because they contain less gas and dust, which means fewer new (and brighter) stars are born
Approximately 60% of all galaxies are spiral
It's not known to any degree of accuracy, but about 66% of all spiral galaxies are barred and about 60% of galaxies in the local Universe are spiral galaxies.
Yes. There are two types of spiral galaxies: "S" (normal spiral) and the less common "SB" (barred spiral, with an elongated center).
spiral galaxies (ours), irregular galaxies, and elliptical galaxies.
galaxie 1, 2, 3, 4 and 5
There at least 60 billion spiral galaxies in the universe because the spiral galaxies comprise of about 60 percent of all galaxies which are about 100 billion.
spiral, eliptical, cartwheel, barred spiral, and lenticular galaxies
because it was spiral
No. It has only 3 big spiral galaxies, but dozens of dwarf galaxies.