Spiral - Elliptical - Irregular DO NOW QUESTION What is an example of each type of galaxy? Spiral - Elliptical - Irregular Milky Way Andromeda M87 Large Magnellanic Cloud Add examples to your Princeton Notes!

Elliptical Spiral Irregular

Galaxy Large groups of stars, dust, and gas Come in a variety of sizes and shapes Can have more than a trillion stars Can estimate how many sun-sized stars the galaxy may have by studying the size and brightness of the galaxy

Spiral Galaxy Bulge at the center and spiral arms Spiral arms are made up of gas, dust, and new stars

Milky Way Galaxy Spiral Galaxy

5. What is an elliptical galaxy? 1/3 of all galaxies Described as a “massive blob” of stars Generally looks like a sphere Has a very bright center Very little gas and dust Contains mostly old stars

6. What is an irregular galaxy? Irregular shaped galaxy “cloud-like” ADD TO NOTES: ¼ of all galaxies Contains large amount of gas and dust A lot of star formation occurs within

10. What are quasars? Among the most distant objects in space “Star-like” sources of light Among the most powerful energy sources in the Universe May be caused by massive black holes in the cores of distant galaxies

Because they are so far away, they are found using radio waves Fun Fact: Because they are so far away, they are found using radio waves Quasars

How the Universe Works: Galaxies

Nebula Large clouds of gas and dust Some glow Some absorb light and hide stars Some reflect starlight Some are regions where new stars form Spiral galaxies usually contain nebulas Elliptical galaxies contain very few nebulas

EX: Crab Nebula In the Taurus constellation Not visible to unaided eye At center is the Crab pulsar

Globular Cluster Groups of older stars Looks like a ball Up to 1 million stars Located in a spherical halo that surround spiral galaxies Also commonly located near giant elliptical galaxies

EX: Omega Centauri Cluster Largest and brightest globular cluster in Milky Way Galaxy EX: Omega Centauri Cluster Located in Centaurus constellation 10,000,000 stars - 12 billion years old Visible to unaided eye

Open Clusters Groups of closely grouped stars Usually located along the spiral disk of a galaxy Newly formed open clusters have many bright blue stars Few hundred to a few thousand stars

EX: The Wild Duck Cluster (M11) Located in Scutum constellation 2,900 stars 220 million years old Not visible with unaided eye