Chapter 13: Stellar Evolution

1.

Sketch an H-R diagram of the evolutionary path of the Sun.

2.

Sketch an H-R diagram of the evolutionary path of a 15 M( star.

3.

Describe how a protostar is believed to form.

4.

What heats a protostar?

5.

What is a bipolar flow?

6.

How can we observe protostars? Why are they surrounded by dust and gas?

7.

What is a T Tauri star?

8.

What is a Bok globule?

9.

What determines when a star becomes a main-sequence star?

10.

What determines how long a star stays on the main sequence?

11.

What makes a star move off the main sequence?

12.

Where do main-sequence stars end up as they evolve?

13.

Why do high- and low-mass stars evolve differently as they become red giants?

14.

Why is it easier for a high-mass star than for a low-mass star to burn helium?

15.

What is meant by a pulsating star?

16.

Why do stars pulsate?

17.

What happens to a solar-mass star when it starts to burn helium in its core? What does it turn into?

18.

What is a planetary nebula?

19.

What is one explanation for how a low-mass star expels its outer layers to make a planetary nebula?

20.

What is left when a planetary nebula dissipates?

21.

What makes a high-mass star’s core collapse?

22.

How do the neutrons form in a massive star’s remnant core? What other kind of particle is made along with the neutrons?

23.

What is a supernova explosion?

24.

What kind of subatomic particles have been observed when a supernova explodes?