Science Tip

1. In your stellar evolution concept map, you wrote about all stars in the universe. What area do all stars start out at?

2. What area do stars spend the most time in?

3. In order to become a black hole, which stage did this star enter after the main sequence?

4. Is your concept map done?

Star Groups

Chapter 27 (p. 561-565)

GalaxyGalaxy

• Def: large group of stars bound by same gravitational force

• Contain solar systems and star clusters

• Nearest Galaxies– Large Magellanic Cloud (LMC) (150 m.l.y.)– Small Magellanic Cloud (SMC) (same)

• Local Group (all within 3 million light yrs)

LMC

Types of Galaxies

1. Spiral• Mostly young stars, gas, & dust

Our Galaxy: The Milky Way

Diameter: 100,000 light-yearsThickness at nucleus: 2,000 light-yearsSun: 30,000 light-years from the center

Types of Galaxies

1. Spiral–Barred Spiral

Types of Galaxies

2. Elliptical

•Older stars, no dust or gas

Types of Galaxies

3. Irregular

•Mixture of Galaxies

•- Old and New

NCG 6946

M100

NGC 3370

NCG 4565

M104 (The Sombrero Galaxy)

M-81 (Andromeda Galaxy)

http://www.astronomy.com/photogallery/gallery_small.asp?idObjectLibraryGUID=%7BDBE18771-A888-11D4-9183-000629551DBC%7D

M105

NGC 3384

M-84

NCG 4636

Merger of two Spirals to form an Elliptical

Centaurus A

NCG 1705

Star Cluster in M10

Cluster in NCG 6397

http://www.astronomy.com/photogallery/gallery_small.asp?idObjectLibraryGUID=%7B81F5306F-40BA-4E22-88E7-636D84734994%7D

G1- Globular Cluster

Omega-Centauri

M 80 Globular Cluster

NCG 6822