A common system, known as the Hubble tuning fork diagram, divides them into two main types: normal spirals (S) and barred spirals (SB). The pattern itself rotates more slowly than the material within it, maintaining its shape over billions of years.
Spiral Galaxies Definition Classification Subtypes
Finally, the halo is a roughly spherical region of sparse stars and dark matter that extends far beyond the visible disk, providing the gravitational scaffolding necessary to hold the galaxy together. Type Description Example S or SBa Tight, well-defined arms originating from a large bulge.
Surrounding the bulge is the galactic disk, a flattened structure where the spiral arms reside. Normal spirals, designated Sa, Sb, and Sc, feature a central bulge that grows larger and a disk that becomes more rectangular as the classification moves from 'a' to 'c'.
Spiral Galaxies Definition Classification Subtypes
In contrast, barred spirals possess a bar-shaped structure of stars running through their center, from which the spiral arms emerge. Classification and Variants Spiral galaxies are further categorized based on the prominence of their central bulge and the tightness of their spiral arms.
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Looking at Spiral galaxies definition from another angle can help expand the discussion and give readers a second clear paragraph under the same section.
More perspective on Spiral galaxies definition can make the topic easier to follow by connecting earlier points with a few simple takeaways.
