Galaxies have a spiral pattern due to 'density waves' in the galaxy. Stars in a galaxy orbit much faster than the spiral arms, and pass through the spiral arms quite quickly. However many stars share...
Galaxies are the shape that they are because of the way the gas and dust that made them were moving. When relatively stationary gas and dust begin to coalesce, the result is irregular or globular....
Spiral galaxies look like flat white disks with yellowish bulges at the center and disks filled with cool gas and dust, interspersed with hotter ionized gas and usually display beautiful spiral arms
A spiral galaxy CAN be called a spiral barred galaxy if it has a central bar. About 50% of all spiral galaxies have a central bar. It's nothing more than a central core than resembles a bar - or...