chapter 17

Question 1

hydrogen is converted to helium in the presence of carbon

Answer 1

CNO cycle

Question 2

• hydrogen-1 + carbon-12 → nitrogen-13
• nitrogen-13 → neutron → carbon-13
• 2 hydrogen nuclei + carbon-13 → nitrogen-14→ oxygen-15
• oxygen proton → neutron → nitrogen-15 + proton → ejection of helium-4 → carbon-12

Answer 2

CNO cycle chain

Question 3

begins when a high-mass star runs out of helium, and produces more massive elements

Answer 3

carbon fusion

Question 4

a region on the H-R diagram containing stars that pulsate with a periodic variating in luminosity

Answer 4

instability strip

Question 5

• a variable star that undergoes periodic radial pulsations
• most are cepheid variables

Answer 5

pulsating variable star/ variable star (2)

Question 6

• the relationship between the period of the variability of a pulsating star and the luminosity of the star
• longer period pulsating variable stars are more luminous than shorter-period ones

Answer 6

period-luminosity relationship (2)

Question 7

• observe the period of the cepheid star
• combine the period-luminosity relationship to find the luminosity
• combined that luminosity with its observed brightness to find the distance

Answer 7

3 steps for finding the distance to a cepheid star

Question 8

a variable giant star whose regularly timed pulsations are good predictions of its luminosity; less luminous than cepheid stars

Answer 8

RR lyrae variable

Question 9

hot, luminous, extremely rare stars that are as massive as 150 SM

Answer 9

luminous blue variables (LBV)

Question 10

the energy required to break the nucleus into its constituent parts

Answer 10

binding energy

Question 11

thermal energy is carried out of the center of the star by neutrinos rather than by electromagnetic radiation (light)

Answer 11

neutrino cooling

Question 12

• an atomic nucleus absorbs an energetic gamma ray and emits some particles
• absorbs thermal energy and reverses the results of nuclear fusion

Answer 12

photodisentigration (2)

Question 13

electrons are absorbed by protons in atomic nuclei, forming neutrons and releasing neutrinos

Answer 13

charged destruction

Question 14

a supernova explosion where the degenerate core of an evolved massive star suddenly collapses & rebounds

Answer 14

type II supernovae

Question 15

• the formation of low-mass nuclei during the first few minutes after the Big Bang
• responsible for the creation of massive elements in the universe

Answer 15

nucleosynthesis (2)

Question 16

an atomic nucleus forms a heavier nucleus after colliding with a neutron and creates heavier elements

Answer 16

neutron capture

Question 17

a helium nucleus is captured by another nucleus during nucleosynthesis

Answer 17

helium capture

Question 18

• the neutron-degenerate stellar core left behind by a type II supernova
• has a radius of 10-15 km
• density is ~ 10^18 kg/m cubed

Answer 18

neutron star

Question 19

• a rapidly rotating neutron star that beams radiation into space n 2 search-light beams
• strong magnetosphere

Answer 19

pulsar (2)

Question 20

a binary system where the mass from an evolving star spills over onto a neutron star

Answer 20

x-ray binary

Question 21

bursts of gamma rays lasting a few miliseconds-minutes that originates from a neutron star merging

Answer 21

short gamma-ray burst

Question 22

• an expanding cloud of debris from the explosion which occupies that place in the sky
• glowing gas expanding away from the central star 1500 km/s
• crab pulsar at the center of the nebula flashes 60 times each second

Answer 22

crab nebula (3)

Question 23

a spherically symmetric, highly condensed group of stars, containing tens of thousands to millions of members

Answer 23

global clusters

Question 24

a loosely bound group of dozen to thousand stars that formed together in the disk of a spiral galaxy

Answer 24

open clusters

Question 25

• astronomers use main-sequence fitting to determine the distance to a cluster
• all the stars in a given cluster are approximately the same distance from earth
• astronomers use clusters to study stellar evolution

Answer 25

cluster distances & ages (3)

Question 26

• the location of the most massive star that remains on the main-sequence
• indicates the age if the cluster

Answer 26

main sequence turnoff (2)

Question 27

more reddish stars in its cluster

Answer 27

old clusters

Question 28

more luminous, bluer stars in its cluster

Answer 28

young clusters

Question 29

a group of stars with similar ages chemical composition, and dynamic properties

Answer 29

stellar population