Star Clusters: Crash Course 35

What is a group of two stars orbiting each other called?

• Cluster

• Binary

Which type of star cluster is loosely bound and can contain thousands of stars?

• Nebula cluster

• Open cluster

What did Galileo discover about open clusters?

• They are single massive stars

• They are composed of many stars

How are stars in a cluster bound together?

• By cosmic dust

• By mutual gravity

What is the typical distance between stars in an open cluster?

• Less than 1 light year

• Exactly 2 light years

How can the age of a cluster be determined?

• By the color of its stars

• By the most massive stars still on the main sequence

Why do most clusters evaporate over time?

• Because of expanding universe

• Because of gravity interactions among stars

What makes globular clusters different from open clusters?

• They have hundreds of thousands of stars

• They contain fewer stars

Why are globular clusters considered great laboratories for stellar astrophysics?

• Because all stars in them are the same age and distance from Earth

• Because they contain only blue stars

What phenomenon contributes to the formation of blue stragglers in globular clusters?

• Stars colliding and merging

• Nuclear fusion