Lenticular, spiral, and elliptical galaxies are three major types of galaxies, each with distinct characteristics. The Milky Way galaxy, to which our solar system belongs, is classified as a spiral galaxy. Here are some key differences between these types of galaxies:
Lenticular Galaxies: Lenticular galaxies, also known as S0 galaxies, exhibit a disk-like structure similar to spiral galaxies but lack prominent spiral arms. They have a central bulge and a flat, rotating disk of stars and dust, similar to spiral galaxies. However, they generally have less interstellar gas and dust compared to spiral galaxies. Lenticular galaxies also tend to have older stellar populations and lack active star formation. They are often considered an intermediate type between elliptical and spiral galaxies.
Spiral Galaxies: Spiral galaxies, such as the Milky Way, are characterized by a distinct spiral arm structure originating from a central bulge. They possess a rotating disk of stars, gas, and dust, with prominent spiral arms winding outward from the center. Spiral galaxies typically have ongoing star formation occurring in their arms, and they often contain younger stellar populations. The spiral arms can be tightly wound (called "tightly wound spirals") or loosely wound (called "loosely wound spirals"), affecting the overall appearance of the galaxy.
Elliptical Galaxies: Elliptical galaxies are named after their elliptical or spherical shape. They lack the spiral arms and disk structure found in spiral galaxies. Elliptical galaxies are predominantly composed of older stars, with little interstellar gas and dust. They exhibit a range of sizes, from small dwarf ellipticals to massive giant ellipticals. Elliptical galaxies are often characterized by their smooth and featureless appearance, without significant ongoing star formation.
In the case of the Milky Way, it is a large barred spiral galaxy. It consists of a central bulge, a rotating disk with spiral arms, and a bar-shaped structure extending from the center. Our galaxy contains a diverse range of stellar populations, including both younger and older stars. The Milky Way also possesses significant amounts of interstellar gas and dust, enabling ongoing star formation.