Ch. 22

Question 1

Zero-Age Main Sequence

Answer 1

(left-hand edge of main seq. band) when a star stops contracting and begins to fuse hydrogen in its core

Question 2

Rate of Fusion

Answer 2

Depends very strongly on star’s core temperature

Question 3

Lifetime on Main Sequence

Answer 3

O5 - 1 million

M0 - 200 billion

Question 4

Betelgeuse

Answer 4

• Red giant at shoulder of Orion

- Very large extended atmosphere

Question 5

Globular Clusters

Answer 5

(1) (i.e. Omega Centauri) nearly symmetrical clusters
(2) about 150 known in our Galaxy
(3) spherical halo w/ central bulge

Question 6

Open Clusters

Answer 6

(1) Found in disk of Galaxy
(2) Only containing several dozen to hundreds of stars
(3) Dimmed by interstellar dust concentrated in disk
(i. e. Pleiades aka Seven Sisters)

Question 7

Stellar Associations

Answer 7

(1) Group of extremely young stars w/ 5 to 50 bright O & B stars
(2) Spiral arms

Question 8

H-R Young Cluster

Answer 8

High mass stars have already arrived at main sequence while lower mass still contracting

Question 9

H-R Older Cluster

Answer 9

Most stars on sequence with high mass stars leaving sequence

Question 10

Triple-Alpha Process

Answer 10

As helium core sinks inward, grows much hotter → three helium atoms can begin to fuse to form single carbon nucleus

Question 11

Helium Flash

Answer 11

In low mass stars, entire core ignited in quick burst of fusion

Question 12

Planetary Nebulae

Answer 12

When stars die and sweep outward into the shells of material ejected

Question 13

Interior Structure of Last Phase Massive Star

Answer 13

Iron Ash → Silicon, Sulfur Fusion → Magnesium, neon, O2 Fusion → Carbon, O2 Fusion → Helium Fusion → Hydrogen, Helium Fusion

Question 14

Temperature range of HR Diagram

Answer 14

3000 K → 40,000 K