Unit 5 Galaxies and Cosmology
Unit 5
Galaxies and Cosmology
By: Briana Polk
Miscellaneous Important Key Words and Facts:
I. TYPES OF GALAXIES:
Spiral Galaxy (S) Spiral Barred Galaxy (SB)
Elliptical Galaxy (E) Irregular Galaxy
(In order of importance…)
1. Spiral Galaxies: (Edwin Hubble, 1936) “The most common type of galaxy that is viewed by observers; It contains twisted collections of stars, stellar remnants, and a diffuse interstellar medium (ISM) of gas and dust”.
Made up of hot young stars
Most spiral galaxies contain a central bulge surrounded by a flat rotating disk of stars. Made up of older, dimmer stars, the bulge in the center is thought to contain a supermassive black hole. The dim light from the older stars can make the bulge difficult to pinpoint, and there are some spirals that lack this characteristic.
Orbiting the bulge, a rotating disk gives the galaxy its distinctive classification. The disk separates itself into arms that circle the galaxy. These spiral arms contain young, bright stars, as well as a wealth of gas and dust. The brilliant stars are the reason the arms are so well defined.
2. Spiral Barred Galaxies:
“A spiral galaxy with a bar-like bulge in the center, extending between the core and the spiral arms. About a third of spiral galaxies have this straight bar of stars, gas, and dust extending out from the nucleus. As with other spiral galaxies, barred spiral galaxies rotate, and new stars form from the dust and gas in their arms.”
3. Elliptical Galaxies: “An elliptical galaxy is a galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile”.
Very little star formation is thought to occur in elliptical galaxies, because of their lack of gas compared to spiral or irregular galaxies.
4. Irregular Galaxies: “An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy.”
IV. OTHER IMPORTANT INFORMATION (test review questions)
”Galaxy” comes
Galaxies and Cosmology
By: Briana Polk
Miscellaneous Important Key Words and Facts:
I. TYPES OF GALAXIES:
Spiral Galaxy (S) Spiral Barred Galaxy (SB)
Elliptical Galaxy (E) Irregular Galaxy
(In order of importance…)
1. Spiral Galaxies: (Edwin Hubble, 1936) “The most common type of galaxy that is viewed by observers; It contains twisted collections of stars, stellar remnants, and a diffuse interstellar medium (ISM) of gas and dust”.
Made up of hot young stars
Most spiral galaxies contain a central bulge surrounded by a flat rotating disk of stars. Made up of older, dimmer stars, the bulge in the center is thought to contain a supermassive black hole. The dim light from the older stars can make the bulge difficult to pinpoint, and there are some spirals that lack this characteristic.
Orbiting the bulge, a rotating disk gives the galaxy its distinctive classification. The disk separates itself into arms that circle the galaxy. These spiral arms contain young, bright stars, as well as a wealth of gas and dust. The brilliant stars are the reason the arms are so well defined.
2. Spiral Barred Galaxies:
“A spiral galaxy with a bar-like bulge in the center, extending between the core and the spiral arms. About a third of spiral galaxies have this straight bar of stars, gas, and dust extending out from the nucleus. As with other spiral galaxies, barred spiral galaxies rotate, and new stars form from the dust and gas in their arms.”
3. Elliptical Galaxies: “An elliptical galaxy is a galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile”.
Very little star formation is thought to occur in elliptical galaxies, because of their lack of gas compared to spiral or irregular galaxies.
4. Irregular Galaxies: “An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy.”
IV. OTHER IMPORTANT INFORMATION (test review questions)
”Galaxy” comes