Spiral Galaxies
Spiral galaxies are a type of galaxy characterized by a distinct spiral arm structure. They are one of the three main types of galaxies, along with elliptical and irregular galaxies. Spiral galaxies are often very large, containing billions of stars, as well as dust and gas. The spiral arms of these galaxies are regions of active star formation, where new stars are constantly being born.
Structure of Spiral Galaxies
Spiral galaxies typically have a central bulge, surrounded by a flattened disk. The disk contains the spiral arms, which extend outward from the bulge in a spiral pattern. The spiral arms are made up of a combination of young, hot stars, as well as interstellar gas and dust. The bulge of the galaxy usually contains older stars, and may also harbor a supermassive black hole at its center.
Classification of Spiral Galaxies
Spiral galaxies are classified into two main subtypes: "normal" spirals, denoted as "S" galaxies, and barred spirals, denoted as "SB" galaxies. Normal spirals have a distinct bulge and spiral arms, while barred spirals have a central bar-shaped structure extending from the bulge, with the spiral arms emerging from the ends of the bar.
Examples of Spiral Galaxies
Some well-known examples of spiral galaxies include the Andromeda Galaxy (M31), the Whirlpool Galaxy (M51), and the Pinwheel Galaxy (M101). These galaxies are easily observable in the night sky and have been the subject of extensive study by astronomers.
Study Guide
.◂Science Worksheets and Study Guides Sixth Grade. Weather patterns
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