Galaxies!

Did you know that there are several different types of galaxies? Well, there are. Spiral Galaxies, Barred Spiral Galaxies, Elliptical Galaxies, and Irregular Galaxies all exist in the cosmos.

Spiral Galaxies, like our own Milky Way, are characterized by arched "lanes" of stars. Spiral galaxies generally have solar masses anywhere from 10^9 to Normal 0 false false false MicrosoftInternetExplorer4 4x10^11 and solar luminosities of 10^8 to 2x10^10. Spiral galaxies are further classified according to the "texture of the spiral arms and the relative size of the central bulge.

Similar to Spiral galaxies are Barred spiral galaxies. The spiral arms originate at the ends of bar-shaped regions running through a galaxy's nuclues. A barred spiral galaxies have similar solar masses and solar luminosities as regular spiral galaxies and are subdivided by the size of the central bulge and characteristics of the spiral arms.

Elliptical galaxies, surprisingly enough, have distinctively elliptical shapes and no spiral arms. They contain almost no interstellar gas and dust, and so almost no new satr formation takes place in them. Elliptical galaxies have solar masses of about 105 to 10^13 and solar luminosities of anywhere from 3x10^5 to 10^11.


Irregular galaxies are galaxies that don't fit into another category. They are usually rich in interstellar gas and dust and contain both old and new stars. Irregular galaxies have solar masses anywhere from 10^8 to 3x10^{^10} and solar luminosities anywhere from 10^7 to 10^9.